Tune selection and reading what the crowd wants - Lawler and Morillo are good at this, residents are usually better than one-off guests.
Enthusiasm without being full of yourself - Lottie is a good example, Morillo (madly in love with himself) fails miserably.
Throwing in something you wouldn't expect - like Harry Romero dropping the Human League in Pacha.
Knowing when to drop the big tune without overdoing it - not that hard really.
A bit of skill on the decks, but not at the expense of the music.
Interaction with the crowd - nobody does it better than the Tidy Boys.
A bit of effort. It never ceases to amaze me how many big name DJs turn up, go through the motions, play an average set when you've heard them play great ones, disappear as soon as they're done without acknowledging the crowd and even go on the decks pissed. Jules is a serial offender on all counts.
Having a really great tune of your own also helps. When Emerson drops Born Slippy or Groove Armada play Superstylin' the place is guaranteed to go ballistic.
