Don’t: Overdo the reverb and other plugins.
Reverb makes music from an instrument produce lasting sound across the track. Many instruments (for instance, acoustic ones like guitars) have a natural reverb effect. One mistake that many novice engineers make is overdoing their reverb, which can create a muddy, soupy-sounding track. Apply it moderately to help create a dynamic mix with a broad range across the high and low ends. If your mix starts sounding too far from what it was intended to be, dial it back a bit.
Do: Make sure your levels are balanced.
All of the compression and EQing in the world won’t help you if you’ve got tracks with levels all over the place. The normalize effect in Adobe Audition can be extremely helpful in setting this up. This effect applies gain to the amplitude of your tracks to bring everything to a constant and consistent level, which reduces the amount of highs and lows you get in the final mix.