In mixing, it's all about knowing your tools. EQ, reverb, compression. EQ is a big part. You can bring out lows, make the clap slap hard and so on. But, it's not really something I can tell you to do... It's all about doing it and finding your own tricks. Listen to your favorite CD and try to make it sound like it. Play with the EQ, layer, and add effects like reverb and delay. But, only use reverb and delay for the finishing touches.
Get to know all the wordology:
*Shelving frequencies (is when you shelf a certain frequency and NOT CUT IT) *If you cut the lows on a bass, you take the life out of it. YOUR CUTTING THE frequency. But, it you shelf, you only target a frequency that is too boomy or giving you problems, not taking out important frequencies. That's how you make a tight full 808 and not a weak one...
*Cutting frequencies (OK on vocals, Bad on instruments)
*Boosting frequencies (just bringing up a frequency)
*Rolling off frequencies
*DB boost or cut