Hey Dave, the best way is to just do it. But remember, less is more. It also depends upon what type of eq you are using, graphic or parametric. But here's a method to help you narrow down eqing. I'm going to assume you're using a graphic, if I'm wrong just tell me.
First, listen to the song or track without any eq. Then pick a frequency, any frequency, and play with it. At this point just use one freq. Boost it, listen, cut it and listen some more. After you can tell in advance what a cut or boost is going to do go to another freq (return the first to 0). Become just as familiar with it as the first one.
Now listen to what they do together. Boost one, cut the other, boost them both, cut them both, etc. Don't worry about getting a 'good' sound. In fact you may grimace now and then ~grin~. But you will also find a couple of good sounds too. Write them down. And send them to me (just kidding). Continue with all the bands.
This may seem like a long drawn out process but it's designed to give you a better understanding of what the eq is doing. And understanding eq is the only way to master it. Charts and articles are good and handy to have, but nothing beats listening.
One other quick note: if you adjust 20 or 30 levels of eq that's way too much. If you have to do that much eq it's better just to record the song/track again.