I just finished my first Jam and this are my tips:
-Get up early, have a good breakfast and start (Of course this depends if you work, study)
-Use a game engine you like or enjoy
-Don't be afraid of using YouTube tutorials for everything (Creating menu, how to do this or that)
-Manage your scope, go for something small with a few game mechanics. During jams we don't have much time. And sometimes trying to fix a bug could take a long time.
-Use free assets (SFX, Music, Sprites, etc)
-Take a break when you need to. But keep the focus on the game and don't procrastinate too much.
And have fun :D