check out this post by DJ Endo at Dubspot. Alot of great things in there. I did most of what he has to say in there and when I want a particular type of track I search by Genre, Mood, and Descripitors and I have no trouble finding what I’m looking for, often several possibilities come up that can go with the direction I want to move in with my set.
I think the key is getting your playlists to work for you and almost turning it into a google search engine. Just find what method works for you really. I would say to first clean out all your old tracks you dont realy play and start with tracks you want to keep or are requested often etc;
http://blog.dubspot.com/how-to-create-smart-playlists-organize-your-music-in-itunes/