I got a wonderful suggestion via Twitter (from @PurpleArti) asking for an article on how I organize my music. It's actually a craft, and many people don't have the patience for it. It takes time and dedication. If you aren't a bit OCD, download folders can spiral out of control. My way works for me, but you might be comfortable using only a couple of these methods with your own software and process.
For a DJ, keeping your files organized is as important as keeping your hardware in fantastic shape. You want to be able to jump from genre to genre, know where your songs are, and not have to search for something that you just realized would fit perfectly into a set from outside of your software. Here's how I organize my files, step by step.