I'd like to add to the list above:
- Get familiar with the basics before the jam. You'll want to know how to move a guy on the screen, how to make a score, how to make a state machine. Clearly you won't know how to do everything, but you should give yourself a toolkit of basic skills so you don't spend you're entire day making your player move correctly on the screen. I really wanted dialog in my first game jam I participated in and I spent an entire day on learning how to do that. This caused me not to finish :/
- META-STRATEGY: PRE-COOK OR BUY EASY MEALS AND SNACKS!! Unless you've got a wife, girlfriend, boyfriend, or SO who is wiling to keep you fed during this ordeal, I highly recommend picking up some TV dinners, snacks, and drinks for the three days. Nothing is worse than realizing your hungry and then spending the next 2 hours cooking because you're on an involved diet and you could have been making your game better. Grab, reheat, go.