How to DJ: Skills, Attitudes and Basic Mixing Techniques

This article was originally writting in December 2000 and deals with the problem of playing live. It argues that using MP3's ain't that bad (at that time this was still a big 'no-no' for part organizers) and allthough the article starts to feel old, we leave it here as a 'blast from the past'. Enjoy it.

Introduction

This page covers some comments and opinions on the basic skills and attitude of a DJ. How does a typical audience behave ? What they expect and how they react. Afterward we give a set of recurring, but wrong, ideas about 'DJ-ing'.

The Audience

The audience is the most important of all. They are the final judge of what you're doing. A party without people is no party. It is as simple as that. People can be at a party for a number of reasons

They are there because they are organizing the party.
People can come for social contact.
To take pictures of the room (I hate the Japanese tendency to run around with half a ton of lenses and photo machinery)
To drink & forget their problems. As the night goes on, people will become drunk or stoned (or both at the same time).
To dance and have a good time. These people are the ones which will be your judge.
People can also be there because they came along with other people. These people aren't expecting anything. So don't expect anything from them.

So, a party is not that difficult at all. Nevertheless some DJ's have quite a strange picture of what's going on at parties.

Dirty Trick: If you throw salt over the floor before people come in then the audience will drink more later on the evening.

Some Recurring Misconceptions

A number of DJ's have the tendency to act as if they are god. This is wrong, they are not. A number of these wrong attitudes are stated below.

Playing music is not only using your intuition. The times you have an aha-erlebnis and you know what to play will be very small. If you play 300 songs overnight, 80% will be based on ratio. Only 20% on 'feeling'. Especially in the beginning because you will be nervous and will need to fall back to your technical skills.
Do not expect everybody likes what you are playing. Often DJ's are very explicit about the music they like and the music they don't like. Don't be like that. It is not because you are playing music, that other music is bad, also don't insult somebody if he doesn't like what you like. You are not the center from which music comes. (technically this is true, but it doesn't go any further than that). There will be songs which you like, which nobody else will ever like, try to detect these and cut the crap, how painfully it might be to play a night without your favorite songs.
Learn different styles. New influences are absolutely welcome for a DJ.
For most DJ's the following holds true: you are playing for the audience, the audience isn't there for you. So, look at how people react to your music. You are playing music either for money, for personal reward or because nobody else wants to do it. In any case the result: 'the audience stays and is happy' is the most important.

And the worst kind of god-attitude that is embodied within current day DJ's and Party-organizers is that:

DJ-ing with MP3's ain't cool.
It doesn't sound the same.
Sorry, we only do turntables.
You don't have to do anything yourself
and so on..

It is just required to point out that more and more DJ's nowadays use CD's, which weren't cool enough a while ago, then we can safely say that this kind of 'oops, I don't like it when the world changes'-attitude won't bring them any further.

The Correct State of Mind

On top of these strange attitudes, we have DJ's who wants to use certain drugs to play. They probably think it is cool to be high (or down, or slow or fast). I wouldn't advice to behave like this: stay sober. The essence of whatever you are doing is to feel good. If you don't you will not have enough focus to do what you are payed for. If you want to gain some confidence, be fit! Do exercises every day and eat well (healthy food). It really helps to do some exercises before I go to a club (even if it's only DJ's meeting not a party). But, let's skip this 'how-fucked-up-is-the-DJ-exactly' crap. Let's continue with the real work:

Indexing and Selecting Your Music

Whether you have CD's, vinyl or MP3's, have an index at hand, sorted by style, annotate with the BPM and marked with the 'sound-color'. This list should contain cross references between styles: 'switch to this style using this song'. On top of this style list, also have a full index by name available every time you play.

Creating such a list takes a lot of time. You can easily spend months to create it, but when you have such a list it is your treasure. This will be half the money you make with DJ'ing. So never give this away.

Warning: A mistake often made is only to exploit the index and not to explore anymore. This is wrong because you might encounter better mixes. It's also wrong because you're definitely not looking at the audience, and above all it's wrong because DJ'ing isn't fun anymore this way.

Tempo

It is also a very good idea to accurately measure the tempo of all your songs (that is up to 1/100 of a BPM). Programs such as BpmDj, BpmCount or BpmLive can help you with this. The tempo in general is necessary to a) match the tempo of the new song to the old song and b) set the tempo of various effect boxes exactly to the current playing tempo.

Finding Cool Music

Tip #1: Comb the aisles of your local record store, hit all the online music outlets and follow the dots from song to song and artist to artist (this is the fun part of DJ'ing - research).

Tip #2: ask producers for previews of music and songs that will come out.

The sound quality, timbre, color is created by the original artist. A DJ cannot modify this much. Your set on the other hand belongs to you and the artist has little control over it. What audience you will see depends on the party organizers.

This means that if the songs is not good or boring that it is not your responsibility to fix it. You should select songs that are already good in the first place. How you weave them together in your set is on the other hand your task. Even 5 minutes of crappy songs can ruin your set, so be sure to use the best music you find.

New CD's

Often if you buy a new CD you want to know what is usable on that CD. In general if I get a new CD I play it from front to back. If I survive that first play then it is a good record. If not then hopefully there were some excellent and remarkable good songs in it. Once this is done, I'm interested in finding mixes that fits to the good songs. This requires some fiddling. Which song can be linked to this cool song. Basic trial and error. I do however only work with the songs that are worth it. I don't spend much time on songs that 'might be good if handled like this or this'. Bottom-line is that these were not sufficiently good in the first place.

Select Music

A good strategy to play music for a specific audience is to rely on a number of prototype people you know that like the music that is typically played at a certain kind of party. Think: 'would this person like this music ?' This works quite well !

Basic Mixing Techniques

The Mixing Desk

Now (halfway the guide), let's start with the basics. The mixing table. A normal mixing table has a number of mono and stereo channels. We are only interested in stereo channels. Every channel has

A gain. This can be found on all mixing devices. This changes the pre-amplification of the signal before it goes to the volume fader. The gain should be set as high as possible without clipping or distorting the music.
An equalizer. Depending on the mixing table it is a parametric or non-parametric equalizer. A non parametric equalizer is a filter which weakens or strengthens a signal in a certain frequency range. E.g, if a mixing table has three knobs, one with 11kHz, one with 3kHz and one with 100Hz it is a non-parametric equalizer. On the other hand if we have a mixing table with 4 knobs, 11kHz, 100Hz and a knob which let you choose the frequency and another knob which let you choose the strength of that frequency then it is a parametric equalizer. When changing the equalizing, the gain has to be changed too. E.g., when cutting down the bass, the gain can be raised.

Notice that the human ear becomes accustomed to a certain frequency spectrum. So, avoid the trap of equalizing everything too sharp. If you see (you won't hear it) that your equalizing is completely out of balance fix it slowly. In fact not that many (modern) songs need equalizing anymore. Secondly, some DJ's like to turn their three equalizer buttons completely to the right when they play. This should not be done because it modifies the sound and often removes critical information from the music. Normally the sound is unmodified if all equalizers are set to 0, not to +15dB.

A volume slider, which allows you to change the volume which goes to the main mix. Most mixing tables can go to +15 dB, but there is no use in that. Avoid the trap of raising the volume relatively to each other until the two songs are playing at +15 dB and you can't get higher. Volume 0 should be the maximum volume you apply.
A PFL button. PFL stands for pre-fader-listening. If you push this button, regardless of the volume fader you will get the complete signal in your headphone/monitors.
A monitor is a set of boxes next to you which gives you what you hear in your headphones.
A balance, which lets you choose whether you hear the left or the right channel for stereo channels. For mono channels the balance is replaced by a pan, which lets you direct the signal to the left or to the right. For mixing purposes a balance is not necessary. Just don't forget to place it in the center :)
Possibly, AUX sends. These are buttons to change the volume of the channels going to an effect unit. These can be pre-fader or post-fader and are often no use for a DJ without an effect unit.
A mute button, which mutes the sound completely: nothing is send out over the AUX sends, nothing is send to the main mix and sometimes nothing is send to the pre-listener. The latter depends on the kind of mixing table.

Aside from all these things for every channel we also tend to find the following

A volume indicator which shows you the pre-listening signal, or if there is nothing to pre-listen the main-signal.
A main volume, which changes the volume in the room. This typically builds up as the room gets filled. But shouldn't be touched normally. If you want to change the volume, change the channel-volume, or gain if it was set too low.
A phones volume, which changes the volume send to your headphone.
A monitor volume, which changes the volume of the speakers next to you.
A cross fader between two channels

Mixing Two Songs

So, when we want to throw in a new song (song B),

Place the volume slider of channel B to zero
Set the gain of channel B to zero
Push the PFL button of channel B. Be sure that the PFL of channel A is off.
Change the gain until we have maximum signal without clipping. Do not touch the volume slider. If you do this the audience will hear what you are planning to play.
Now change the equalizing if necessary. For most songs not much equalizing is needed, unless you are playing very old songs of course. Don't equalize everything too sharp. It is quite easy to hear nothing at all if you don't boost the high frequencies. Don't do this. Change the volume of the headphones or increase the gain if possible.
After equalizing, maximize the gain again. If you cut the frequencies, the gain is not maximum anymore.
Now the real work can begin, look for a good position to kick the song in.
While sliding down channel A, slide up channel B.

Technically this is not difficult at all. However, this scheme should be remembered very accurately and practice is necessary. Otherwise, one of the steps is easily looked over. Especially checking the correct gain is important because it avoids 'not-loud-enough, so let turn up the volume a bit more, oops can't go further...'-problems.

Playing MP3's

If you want to play MP3's, be sure to have spare parts (an extra computer for instance) at hand. One PC with two sound cards is possible but you still have your single point of failure. Use a good sound card, with a good sound quality.

Have all music on both PC's (if one fails you can continue with the second PC), connect them with a small hub if you want. Also, have CD's at hand to continue when both PC's fail.

When playing MP3's, using Winamp

There exists a Winamp cross fading output if you are forced to work with one PC.
have a suitable CD inserted in a CD-player at any time. Windows has the nasty tendency to offer you a blue screen of death. In that case immediately' switch to the CD, which should be ready.

When playing MP3's, using Linux (which would be the more sensible choice given its stability)

Be sure to switch of crond if you have a slow machine.
XMMS has also a cross fading output.
Shameless plug: BpmDj (http://bpmdj.yellowcouch.org/) offers the solution to solve your DJ-ing problems.

Digital Distortion ?

Some of the current day digital sound cards (like the Ensoniq chips which can be found in all new sound blaster cards), have the tendency to increase the level of your signal higher than possible. This result in digital distortion which is at least ugly. To avoid this don't set your PCM-volume to 100% but place it at 80% (or even less).

Changing Tempo & Accuracy of Pitch Shifters

If you want to do beat mixing you need a way to change the tempo of your music. Since this is done by stretching or shrinking the time the music plays, the music will also change in pitch. If we stretch the music the pitch will go lower, if we shrink the music the pitch will rise. The question now is whether the standard pitch shifting software is good enough ? We need BPM's with an accuracy of 0.05 BPM. At 160BPM this requires us the ability to shift the pitch with 0.0003125 %. At 120BPM this requires that we have the ability to shift the pitch with 0.00041666... % The best pitch shifter I encountered till now is AlsaPlayer. This program can shift the pitch of music with 0.01% with is definitely not good enough !

Now, even if they are not accurately enough, it is possible you want to use things like AlsaPlayer (it is good software after all). If that is the case, I want to warn for one thing. Suppose we have song B at tempo 140 and song A at tempo 135. We want to match those two songs. Therefore we calculate the pitch-shift, but instead of dividing 135 by 140, we divide 140 by 135. We see a number (1.03703...) larger than one, while we expected a number lesser than one. As such we take the difference with one (0.03703...) and subtract it from 1, which gives 0.962962... (Not so) Strangely, this is another result than 135 divided by 140, which is 0.964285.

Playing Different Kinds of Popular Music

When playing different kinds of popular music, the most important is to know what is popular with the audience. On top of this there are a number of rules.

Play every song between 2.0 - 2.5 minutes. If you play songs longer people will find it boring. If you play songs too short people will become irritated. Of course, a mistake in the 'short' direction is not that bad.
Minimum 4 songs of the same style in a row.
Work your tempo down until you reach a suitable tempo for a slow.
Always play two slows. After the first not everybody has the girl/the boy he/she wants. After a slow, kick in a beat again. No point in messing around with a 'good' build-up. Some (lonely) people are waiting to dance, and the people slowing will leave the floor anyway when you switch to a non-slow.
In the beginning of the night choose your end style of music. After 3:00, 4:00 o'clock people go home when you switch style, so stay to the same style after that.

Switching from song A to B

Can be done when A has the same connotation as B. E.g., Red Zebra after the Sisters of Mercy is quite possible in Belgium for people who likes Gothic.
Can be done when A has the same 'color' as B.
Can be done when A has the same 'tempo and style' as B.
Is done with a cross fading over 5 to 10 seconds. Don't try to mix the beats when you don't have the skills. Nothing is more irresponsible and insane than a DJ in an ether binge. Euhm.... I mean... Nothing is more irritating than two non matching songs over each other with the bass drums interleaved and a DJ trying to fix that live. If you ever happen to be in such a situation (which will occur) just cut one of both songs. The audience will be happy if you do that. When you cut one of both songs you will be disappointed, just remember that it was too late for a subtle mix anyhow.

At every moment have a list of the three/four/five next songs you will play, this should ensure continuity. If people ask something, don't switch immediately, put them at the end of your list, and eventually adapt your list. Trusts people's opinion only when they are happy. Otherwise neglect them.

Don't play killer music. Killer music is music where you loose a lot of people. For example. If you have 32 diagonal spread, seriously drunk people with 16 man and 16 woman, at 6:00 'o clock in the morning do not play a slow. They will go home afterward. (OK maybe that was the intention :). Another example is a blues-party (Hmm... no point in partying if your girlfriend has left, you are broke, your car has been stolen and you are constipated... Still wondering how fucked up people are when they go to blues-'parties'.); if you play at 3 o'clock a Techno-song (even if it is a good one), they will throw beer at you and drag you away. Knowing what an audience likes is as important as knowing what the audience absolutely dislikes. You don't want to play a killer song, not even by accident.

Playing One Style Whole Night

Essentially, it is much easier to play the same style (Techno, House, Acid, and so on) whole night than playing different styles. Of course, you have to know the style before you even think of playing. E.g: don't play Salsa if you don't know shit about it.

Build your music tempo up, instead of playing it down. Tempo breaks are long ambient passages, not slower songs.
Breaks can be found in

lyrics, where a nice lady tells us she is horny (or something like that)
or ambient passages without a bass drum
or snare-rolls which builds up

If you are playing Techno whole night you might want to surprise your audience by slowly removing the bass drum and afterward kicking it in again. Removing the bass drum slowly and kicking it in is better than boosting the bass drum because most installations cut the mid and high frequencies when you boost the bass too much.
If you are playing Techno, you can build your own buildup if you have a parametric equalizer. Set the frequency low, cut everything out at the right moment and start changing the frequency. Be sure to kick in the complete sound at the right moment. (This can be tricky :) Before you do this practice on the installation in the beginning of the evening.

Beat Mixing

The Tempo

Now, something more difficult: Beat Mixing. Beat mixing is mixing two beats exactly over each other during a certain period. The difficulty with this is that different songs have different tempos. In the upcoming discussion we refer to song B as the one which will be mixed over song A. Synchronizing B with A is the first problem, keeping them synchronized is the second. This discussion is aimed at MP3-players.

In general beat-mixing is only possible when the two songs are playing at the same speed. Therefore, one needs to bring the tempo of one of both songs to the tempo of the other song. However: knowing the tempo of a song up to an accuracy of 1BPM is not even enough to keep two songs synchronized over 1 measure. How accurately the tempo of both songs needs to be known is discussed here and here. Generally, you will need to stay in touch with both songs while they are playing.

This however forms a problem because

The tempo of most acoustic songs have is not perfectly constant.
Depending on the technique used, the tempo can be measured slightly wrong.

Therefore , during playing one needs the ability to shift a playing song a bit forward or a bit backward, such that they stay synchronized. This is called nudging. A nudge typically consists of shifting the song 5 to 10 ms. This is around 1/64 note.

Syncing

When a suitable song has been selected and it is playing at the correct tempo one needs to start the song at the correct moment. Typically this moment is at the beginning of a phrase (that is the beginning of 8 measures). Normally, when the song is started it won't start exactly at the moment you intended it. Therefore, you will need to nudge a little bit. This however is not easy because it is difficult to decide whether the song you threw in started too late or too early. For instance, in the figure below, the white line is the time-line of the main song. The red line is the monitor song which has been started too late. The blue line is the same monitor song but started too early. As can be seen, if we only listen to the beats, it is impossible to distinguish whether the song is too late or too early.

Nevertheless, we do not necessarily need to listen only to the bass-drums, we can also listen to the entire song. This however is also a problem because it becomes simply a chaotic piece of audio which is very difficult to interpret consciously. However, unconsciously it is possible to hear the difference. Therefore, one only needs to try to follow the music and focus specially on one of the both songs. The song for which it is easy to differentiate it from the rest and keep on focusing on it is the first song. For instance, in the red case, the song which can relatively easily be listened to is the white one, our main song. Hence, the monitor song comes too late. In the blue case, we will easily focus on the blue song, the monitor song, hence the monitor songs comes too early.

Another pragmatic way to solve this problem is to nudge forward, if the problem becomes worse, nudge two times backward.

Nudging

During the time the two songs overlap the tempo difference between the two songs (even if it is a very small tempo difference) will result in a slight synchronization drift. This is pictured in the figure below

To solve this one needs to know beforehand which song is the slowest one of both. before a mix is done. Solve this problem is easy. Make sure both song are synchronized, now wait until the two beats sound double. Nudge forward. If it becomes better, you should keep on nudging forward since the second song is going a bit too slow. If it becomes worse you should nudge 2 times backward and conclude that the second song is going a bit too fast. To be workable a DJ should maximally nudge every 4 beats, otherwise he has simply a wrong tempo and should change the tempo of one of both. The direction determined by this technique is the direction you need to use to keep them synchronized once they have been synchronized.

Cross fading

When you finally have the two beats exactly over each other in your headphones you want to switch slowly to song B. Before you do this be sure to cut off the bass drum with the equalizer. Otherwise you get a very ugly flanging effect on the bass drums. If the volume is good, switch off song A's bass drum while you turn on songs B's bass drum. This way it will go unnoticed. If you need to nudge to keep the tempo up during fading, watch the hi hats, not the bass drum, you won't hear it.

Take Your Time

Most songs are in a 4/4 rhythm and it is in general a good idea to respect this pattern: multiples of 4. 4 beats in one measure & 4 (or 8) measures in a sequence. If you respect this you will find that you get easily into the flow of mixing. Of course, this requires some practice, but after a while you will actually start using this scheme. Each 4 measures you can change something like cutting away the bass-drum of one song in favor of the other or using the 4 beats/4 measures knowledge to add breaks and gaps in the music at appropriate places. Such breaks will also ensure that the audience does not loose track of the underlying synchronization.

Breaking

Once you have learned how to cross-fade two songs, you might want to experiment with sudden breaks and gaps in the music. This will give the music more punch and keep people dancing.

Sound Effects

Sound effects are nice things since they make the life of the DJ entertaining. There are a plethora of sound effects out there and probably even more effect boxes. In most cases they can be divided in broad categories that reflect the underlying signal processing algorithms. E.g, LFO (Low frequency oscillators), flangers, phasers, loops, reverbs etc. When DJ'ing techno and electronic music such effects can help to spice up your set. The key to using effects is first to know your hardware and setup (the wiring to/from the mixing desk/effect box(es)). Since there are so many possible routing setups it is probably useful to stick to a common routing which is the sound signal that goes to the effect box, which in turn will alter the sound and return it to the mixing desk. There the 'wet' (affected/effected signal) is mixed again with the dry (unaffected) signal. When the effect is over it is often useful to fade out the effect instead of throwing out instantaneously. For hard effects this is necessary to avoid too sudden changes.

A usable strategy to learn to use effect boxes is a) practice, b) record, c) keep a chart handy of what works and when it works. You'll find that you might tend to favor specific effects when you are playing but when you re-listen you'll notice that you might have overdone it, or placed the effect at the wrong place. Below I list my experience with effects

Reverbs

Are an excellent too to add ambiance to certain passages. It can however become somewhat too dense in tracks that require punch.

for pretty boring techno music it can be nice to add reverb to a number of bassdrums and then skip the remaining bassdrums
reverb can also be nice at the end of a phrase to carry the switch from 'high energy music' to a long empty gap.
in empty areas, reverb can add ambiance

Grind Effects

This is a kind of on the fly within measure resampling of a sampled loop. This often leads to 'matrix' kind of effects.

Good for long high pitches notes (violins etc)
Not suitable for bassdrums

Loop Effects

Is an effect where the current playing song is sampled and immediately replaced by a looping version of the short sampled fragment. The result can be useful to build up bassdrum rolls or snare rolls even if that was not present in the original song. The effect is often very invasive, and can be combined with digital filters or flangers. In all cases, the use of this effect should be minimized to once every hour or so, otherwise your set might become transparent

should not be used to switch from song A to song B. The problem here is often that the original song is still in the mind of the listener and is carried over the loop. A sudden switch then to song b is very often inappropriate.
The length of the sampled fragment should match the tempo of the music
This is a heavy duty effect useful in high energy modes, use sparingly

Pan/Bouncer Effects

Is an effect that will move the music from left to right in an automatic fashion. Depending on the number of autopanners and whether they are tempo sensitive or not, a number of interesting things can be done

To alternate between the monitor song and the main song, place the main song in an autopanner which goes L-R-L-R-L-R--- Place the monitor in another autopanner which goes R-L-R-L at the same tempo. The autopanner should of course be a low frequency oscillator
Autopanners work at most places
Can be used at the end of a phrase as a quick alteration before the song continues

[Voice] Samples

Having seen the Goa scene adopt/embrace ridiculously stupid samples I can only comment that samples when used extremely spare (1 voice sample on an entire CD), will make that people remember that song, which is exactly the reason why producers insist on some shitty voice sample. Let me repeat that:

This of course leads producers to suggest that each song should contain some voice sample. However, in the end this works against the song since movie samples and voice samples without sensible meaning are plain stupid.

Delay Effect

Delays are different from reverbs. While reverbs tend to be impulse expanders, delays will copy the signal to itself. From a technical point of view the implementations are completely different. To understand this, try to create a reverb with a delay effect by shortening the delay time. You'll notice that you are actually creating a digital bandpass filter the shorter your delay time becomes. Reverbs don't have this problem. However, it is somewhat more difficult to create reverbs that go on for long times. In any case.

Delays, when they are matching the tempo of the music are excellent tools to add some extra layers to the music.
When they are slightly out of tempo (e.g;. 5/4th of the tempo) they can make the rhythm interesting at places.

Flangers

... add space to stuff. Euhm. Well, yes they add space in general.

useful at the end of phrase before the next phrase starts
flangers are a form of autofilter, so the depth of the effect is dependent on the spectrum of the sound. Therefore adding a reverb to the sound before the flanger can help to have a deeper effect.
flangers don't work well on low frequencies (well they do their work, but it is difficult to use them properly at low frequencies),

Vocoders

Are multirate filter banks that will split the signal in a large number of subsignals, that if combined will produce the original sound again. Of course, it is possible to choose which part of the signal should be reused in the end. These tools are used to have the effect of a 'talking synth', which is a good effect for certain songs and to convey a kind of robot life. Producers nowadays also use this effect to fix the problem of singers that cannot stick to their tone. This gave the very unnatural singing effect and to be honest -> I hate it. If there is a dance song with a vocoder in it I turn it off, mainly because I know that the effect is used for people that cannot sing.

Strategic Considerations

Obtain Preview Music

A good tip to get in touch with producers and managers that can get your career started is to try to find producers for new hot tracks. If you can connect to them you might get previews of new interesting tracks, which can help your own career forward as well.

Fitting your set into the night

A consideration when multiple DJ's are playing is to know your position and in general the main aim should be to preserve the flow of the previous DJ and not make the next DJ his life overly complicated. In a sense, the previous DJ decides what your first half hour will be since you will need to shift from their style to yours.

What you play also depends on the time of night. If you're the star playing at 01:00 (or midnight), you'll probably play some killer tunes to shake that bodies, while if you play at 10:00 you might want to play anything you want :-)

To achieve a nice take over it is also valuable to chat with the previous DJ to check out what style he/she intends to play. obviously that can change, but having some idea can both make you more prepared to jump in, and also be nice to the next DJ but not making your final song something that completely clashes with their style.

In general, one should not be too concerned with the overall layout of the night because this is the responsibility of the party organizers, who should know what you play and planned the night accordingly.

Keep them dancing but offer bar breaks

From the mailing list: As for how I play the night, I have a couple of discs of songs that I know will get people on the floor. I plan the night to flow like a roller-coaster - people on the floor all night looks good, but if you're playing a club you want them to be going to the bar and buying drinks too. I've had a few times when I've played something I thought would keep people on the floor, only to lose them and needed to bring them back with a crowd-pleaser.

Length of your set

The length of your set determines what to can play. If you play for an hour you might want to stick to a limited number of styles. If you play the whole night you might want to alternate styles once in a while and if you play an hour or two hours you can consider your set to be a form of showcase of your capabilities

Stage fear: Know thyself

A thing I noticed with many DJ's is that they often mix too fast and somewhat chaotic during the first 20 minutes of their set. As DJ you will be nervous the first 20 minutes and there is little you can do about it, except to know this and accept it as a fact of life and get over it. Such stage fear is normal and the best thing to do is to breath in and focus on the job at hand and force time to be steady. That is: measure how long you play each song and make sure it is not 40 seconds or so :-) Of course it is pretty normal to make this mistake because you might ask yourself every second: 'how is it going, should I change tracks, style ?'. By the end of the minute you will certainly have decided to change both track and style. Clearly a bad plan. Just relax. And by consciously relaxing you might find that it becomes easier to relax. Well... This starts to sound like some hypnotic regression analysis. In any case, observe the stress, accept it and let it go. That is the trick.

Understressed Rabbits

Then of course there is the opposite problem that some DJ's exhibit. After an hour or so they left the stress completely behind and are at the same stress level as the audience. This is also a bad plan since the audience is there to relax while you are there to work. So there should be a certain stress difference between you and the audience. What I noticed is that DJ's that have fun and laugh and tell jokes often don't mix that well, while those that focus and concentrate on their set do a much better job, although they might not show the smile everybody is waiting for :-)

Of course another source of this problem might be that these DJ's practice their mixing skills on sets of only half an hour or so. In that case they run out of juice after an hour and certainly after 1.5 hour. If you practice: make sure your sets are sufficiently long.

How to learn to mix

Listen to your own mixes after you made them and see what can be done better. On a side note here: something I picked up from educational psychology is to always stop practicing after you performed something good. In this case, after a good beatmix, stop your session. If you do this after a bad mix because you are frustrated then you will not learn new skills.

Some Final hints

Practice: Have a small mixing device at home. You can act like you know everything and are confident, but without skills it doesn't mean a thing! Prepare for hard work behind your gear and train your skills.
Learn from other DJ's: Listen to them and what they do, as well for the global picture, the songs they are playing as the small shifts they make. Listen also at the faults they make and how they could have avoid it. Beware: the better you become, the more frustrating it is to go to parties :)
The day(s) before you play, listen to old, boring music. Music to which you have no affection. Good results guaranteed !
Take enough sound-cables, power-cables and so on with you. Don't expect something will be available. Also take a mirror with you. Some mixing tables are that fixed and unreachable that you will need a way to see.
Don't forget a lamp.
Tape your sessions and listen to them afterward.

Two other problems taken from the mailing list:

Hearing degradation. As much as I try to protect my hearing, when it comes down to it, I'm exposing my ears to high volume for long periods of time. This hasn't been overly bad, but occasionally my ears will ache and hum after too much audio stimulation.
Unwanted attention. Because, at clubs and in festivals there are often people on all sorts of substances, people may come up to you and start talking about random stuff, or be erratic, or demand songs. That's kind of what security is for, but having some big guy stumbling around and getting in your face is not fun. However, this has only happened a couple of times, so it's no biggy... you'd probably get the same thing just dancing on the dance floor to some extent - it's just not as easy to leave when you're DJ'ing! A good phrase to deal with people who come up with requests is to say "I'll see if I've got it".