To the untrained eye, it is a bit overwhelming to look at a spectrum analyzer and try and see what’s going on in a mix. Voxengo makes a free spectrum analyzer VST plugin you can download here. Spend some time with it, or the one included with your application. Insert it to the stereo bus and watch it during playback of your mix. Solo some tracks and try to spot them in the overall mix. Some plugins, like Wave Arts’ TrackPlug, include an analyzer with their equalizer, so you can see what changes when you make your adjustments.

If you place your frequency analyzer plugin on the Master Bus, (usually the track furthest right on the software mixer, labeled Output or something similar) you can have a constant view of your mix. When you solo a track, you will see only that track’s frequencies.

Don’t limit EQ to just boosting an instrument’s dominant frequencies. You can cut or boost, so don’t forget to cut! It is sometimes easier to reduce other instruments that share the range you’re trying to boost. Using EQ is all about making room. Say for example a kick drum is smothering a bass guitar, or vice versa. You take a look at your equalizer and see that this kick is peaking at 85hz, and the bass is doing most of its work between 150 and 200hz. Rather than further boosting both instruments at those frequencies, reduce the kick between 150 and 200hz, and reduce the bass at 85hz.

If you can’t see or hear where they’re peaking, solo the track and use a combination LPF and HPF as an envelope. If you want to hear the bass between 100 and 200hz only, place the HPF at 100 and the LPF at 200. Then you can get a better idea of what it sounds like in that range. Move the envelope around, and find where you can be comfortable cutting frequencies, and where you can’t.