Better than what I've subsisted on for past cons. If you want caffeine to have its full effect, abstain from anything caffeinated for about a week. On the subject of caffeine, don't have too much if you're going to be taking pictures. Rather than spend a lot of time in the dealer's room, use the opportunity to eat something or take a nap. You'll thank yourself later.
Power naps can work wonders.
Shower early in the morning, before everyone else wakes up. Buy the more common stuff like video tapes later on, if you have the luxury. If you can't find something to do, make something to do. When they pay their share, it's like a cash advance on a credit card, but without the surcharges. If you don't have any friends at the con, make some.