Do not undervalue sleep.
There's a great tendency to want to stay up and not miss anything. But, after even only a day of this, you'll lose your ability to appreciate most of it. Everything will be colored by the fact that you are tired. A few hours to catch a few Zs are agood way to help you enjoy everything else.
Also, keeping up on sleep will mean less recovery time after the con. If you don't sleep much while at the con, the workweek afterwards will be very nasty.
Eat balanced meals. Grease is not a food group. Make sure you get some significant vegetable matter - those vitamins go farther than caffiene in keeping you perky. Also, keep yourself hydrated, for similar reasons. Most folk don't get enough fluids even under normal circumstances. Dehydration increases fatigue, tends to cause headaches, and the like.