This is my second successful game jam that I ended up getting into really late and my biggest tips are:
-Get plenty of rest! You'll catch me powering through energy drinks while I'm working but sleep is super important, you'll be a lot more effective with a good nights rest than staying up for 12 hours straight working on a game, I made that mistake once and my game was riddled with bugs.
-Go in with a plan but be prepared to cut out features. This tip isn't only for game jams but game dev in general, don't get too attached to anything even the game itself, sometimes it's best to scrap an entire game and work on something simpler you can get done on time than to over work yourself.
-Don't worry about how other people might perceive your game, most game jams are non competitive so you shouldn't focus on impressing anyone, just focus on completing a game within the game jam's time frame, that's plenty impressive in itself.
-Don't feel like you need to spend every second of the day working on your game, take breaks. Especially if you run into a problem and can't figure out how to solve it, you'd be surprised how often the answer will come to you when you're doing something else like taking a walk, watching a movie, reading a book, etc.
-And most of all, HAVE FUN! Game jams can be stressful, but the majority of the time you should be enjoying yourself.
There are TONS of YouTube videos on the subject and plenty of articles as well. My all time favorite game dev YouTube channel is called Extra Credits, they pack tons of information into short entertaining videos that can really change the way you design and develop your games for the better.
Here's their Game Dev playlist, I've seen every single one of these videos and they're all incredibly informative:
https://www.youtube.com/playlist?list=PLhyKYa0YJ_5BkTruCmaBBZ8z6cP9KzPiX
Hope this helps and good luck on your future game jams.