There are loads of discussions on this very topic. You can search the web to find plenty of them.
My top tip concerns scope. That is the scale/size of a project and how many game mechanics and features it covers. If you're starting out, start small and simple. Think of simple casual games with a single game mechanic.
Another tip, is to do some Godot tutorials beforehand. Don't leave learning basic aspects like player movement, UI, audio, etc until the game jam starts. Brackeys' himself has some good tutorials.
Good luck!