When EQing individual channels, most folks start boosting stuff. The best approach is to cut in order to get rid of what there's too much of (which, when using cardiod mics, is a whole bunch of bass and low mid boost centered at about 200Hz, and a fair bit of upper midrange boost centered somewhere between 2500 and 7500.
The EQ that sounds best with an instrument solo may not work when the instrument is with an ensemble.
Start with the vocals and work your way to the drums.
From:
http://www.padrick.net/LiveSound/Mixing.htm
