Don't do too much, you can do things you don't exactly know about yet - but it's a good idea not to do anything you have no idea on how to do especially if you're new.
If you think you can do it; do it, else; don't - not yet, wait for the end of the game jam.
Otherwise it will be hard trying to complete your game, and it's likely you won't at all (btw, most of this applies to you only if you're new, people who have worked like this a lot usually can find the way and do it within the time frame). The main thing you need to remember is to not overscope - and you should say this to anyone like you, because everyone does - at least once, most of the time it is in something like this with a short deadline. Finding out the things that you can do within the timeline should help people for everything they do.
And don't push yourself too much, especially if you're not the type who stays up in the middle of the night working - then getting an hour of sleep (I'm not exaggerating). If you can't handle pushing yourself really hard, then don't do it. I've gotten myself stuck in a really bad loop, now whenever I'm working on something I'm staying up stupidly late.