Mixing Guidelines edit
As with anything you do in sound engineering it ultimately comes down to what sounds good so use your ears first and foremost, and when possible, compare your with with one you're familiar with/aiming for. An example of this would be matching your audio with a favorite audio track.
Panning - Moving sounds left and right. edit
Keep things balanced, if you pan one guitar left, pan the other instrument to the right. Usually pan things from 15-75% from the center. "Hard panning" (full left or right) is uncommon and considered bad practice except as a deliberate effect.
EQ/Equalization - Changing the sounds frequency balance edit
Changing the amount of bass/middle/treble a sound has, either adding frequencies to enhance the sound or removing frequencies that are unpleasant.
Compression - Turning down the loud peaks & turning up the quiet parts. edit
Compression can be used as a practical tool, to level out the loud and quiet parts of a song/performance/speech, or as creative aesthetic tool to improve the quality of a sound by adding a punch of thickness or clarity.
