Actually, this isn't a Cool Edit question, cuz it's common to all recordists whatever software they're using, but I'll leave it here for the time being and see if it turns into a Cool Edit thread. What this is is a mixing question.
For me, EQ is easily the most important thing in mixing. Sure, compression's useful, and delay, and reverb. But EQ requires you to not only know how to use the software, but to actually *know* about frequencies and how they work. Okay, I'll start.
There are three main ranges of frequencies: lows (20 Hz - 160 Hz), mids, and highs (5K and above). When you listen to your mix in multitrack, listen to each of these ranges. The most common problems are: too much bottom end, making the mix muddy; too much lower midrange, making the mix dark or boomy or masked; not quite enough upper end, so the mix don't sparkle; instruments in the same range masking each other's sound. So what you tend to do is:
* reduce lower end if you don't need it. A highpass filter is *extremely* useful here. I don't use Cool Edit's EQ, cuz I like my Ultrafunk plugin better.
* reduce frequencies in the 200-350 Hz range - not too much, just enough to clear things up a bit
* boost frequencies from about 5K upward, but not every track cuz then your mix sounds awful - just the ones you want to highlight, like vocals
* complementary EQ - if two instruments are masking each other, find a good frequency and then boost that frequency for instrument #1 and then cut the same frequency for instrument #2. It'll make them sound different and make it easier to hear each one distinctly
There's *way, way* more to it than this. This is just to get started.
