Here are my tips (keep in mind that I have only been in a few game jams so I am not that experienced):
-Make the game as simple as possible. I know people say that a lot, but the truth is that it so hard to follow, you always have grand ideas and you need to learn to start with the crucial features and build up from there. It is very important to scale it correctly. Try to have something finished by day, even if it is just one basic mechanic, you want to have a playable game more than anything. Spend the next days improving the visuals, adding more levels, adding sounds and music, improving the code if you can and maybe (just if the game is in a good shape and you still have a good amount of time left) add new mechanics. You want to finish every day with a working game, especially when you get close to the end.
-Try to work with other people. Don't rely on them, but they can help you with things you struggle or don't know how to do yet.
-If there is a problem you just cannot fix, try to do something and coming back to it later or try to do that part in a different way.
-Accept the fact that the final game will not be as good as what you hope for, remember that in your stage this is mainly a learning experience.
I really hope this helps! good luck!