8 hours sleep
4 bottles of water
2 real meals
The last is important con stench is nasty.
I always have a repair kit and first aid kit in my room (or car) just in case as well as two spare sets of batteries for my costumes lights/lightsaber/fans. I can not stress enough that even though the con is meant to be fun you have to make sure you take care of yourself (Dad mode on) and make sure you eat and sleep. I have done the all night con thing and while fun you are a mess the next day and that day is not going to be great fun. Anouther thing is to make sure you do not have too much cash on you. Leave most of your stash in the rooms safe if it has one. Mind your credit cards make sure they are in your wallet and that is sucure. You can always ask a vendor to hold an item while you get the cash while lost cash cannot be replaced. Yes Dad mode is still on be careful who you hang out with make sure you have at least one trusted friend in the group. Not everyone is nice.