I'll second the warm up advice. Do a miniumum of 5 miles with some sprints for a crit warm up. Night befor I usually eat pasta and drink a ton of water. Also try visualizing the race and race situations. Try to see your self in a good field position and maintaining that till the final stampeed. Watch a movie and sleep well. Most importantly leave for the race to give your self plenty of time. I made the mistake once of showing up to a crit that started in about a half hour. By the time I was registered I was at the start line. I don't even know how I finished that one.