First off, don't have everything playing all the time. Mute stuff and turn things down when they're not the main focus. Automate this to make your life easier. Also, make sure your instruments are played in different voicings and ranges. If using
MIDI, change the inversion or move things up or down an octave.
Remember,
mixing isn't just about
EQ and
compression. Sometimes, it's about fixing your arrangement. Don't be afraid to pan things wider than you think you should. Those hard left and right positions are there for a reason. Record things in mono and make your MIDI instruments mono, too. Stacking stereo instruments on top of each other can make your mix sound less stereo. Mixed mono will give you a wide...