I might be duplicating some of the already posted great advice but...
Before going to a quilt show, I go through my stash and look for things that I bought (because it was oh-so-cute!) and cut swatches to find things to go with it. I usually take a look though my pattern box (ok, boxes) to remind myself what and how many I already have, that keeps from buying duplicates and reminds me to only get a new pattern if its hard to find or just that great! Take a small note book that you can writing notes with pattern/tool/fabric names. If I see something I really like at a booth I'll note it on the back of their card so I can call them later if/when I've had time to consider ..."do I really want to spend money on that"...or if I'm not sure I already have it...
Take a camera! I always ask first, but have never been told not to take a picture.
Lastly have a fabulous time!