Many people do things differently, but like most things, there seems to be few constants.
To say what has been said already again.....
Bass in the middle.
Be carefull with compression.
Subtract EQ rather than boost.
I'm sure you'll find a fair bit of stuff to read on the net, but just keep in mind that there are people in the music industry who are paid for mixing and mastering, so getting your music down is the most important thing - luckily it's the most fun part too.
