Yo! You should check out FutureProducers.com and do a search on EQ. They have many great posts on the subject. Of course, people have different opinions on the subject, but you can find what you need to get you started.
My opinion about EQ is that you should use it as a last resort. Get your mix right first and this will eliminate a lot of the need for EQ. There is no single way or formula to EQ. There is no one-size-fits-all template that you can apply that will work for every track.
Start out by choosing sounds that are the highest quality you can get. Then "space" the different instrument sounds in your track by using pan and delay. This way, all of the sounds don't share the same space. Also, I listen to my finished tracks with the volume as low as I can hear it. Doing this, I'm checking to see if I can still hear all of the instruments in the mix.
Then, I listen to the track with the volume as high as I can stand - listening for instruments that appear to be "too loud". After checking my mix this way, I save it and leave it for about a week. Yeah, it's no good to try and finalize the same track you've been working on for hours. You need fresh ears.
During that time, I listen to "reference tracks" from my favorite artists who have the sound quality that I want for my track. After about a week, I listen to my track to determine if the mix is still good. By then, I can immediately hear if the track needs EQ.
It's important to know the frequency ranges of the instruments you are using in your track. A good frequency chart can be downloaded from SoundOnSound.com. This will help you to see where you might have potential problems with different instruments clashing at the same frequencies - before you even use the instruments.
If I use EQ, I start by "cutting" frequencies (turning them down) first. For example, if I hear that the Bass is clashing with the low piano, I might cut the high end bass frequencies first, then listen before I do anything else. Cut frequencies first.
After I go through all of this, I'll take my track to someone who knows what he's doing - an engineer. I ask questions and listen to what he says about the track and take notes.
Again, read the opinions of others, get the knowledge about the instrument frequencies, experiment and work with an engineer.
Grace and Peace!