Hello Alex Taco, I have been in the Jame Gam community for a while now, and here are the advice ı can give for you:
Not too complex - Make it simple, not too complex. Mostly 2D games are made in this jam.
Keep it clean - Don't mash UI everywhere, keep the graphics and the UI clean for extra votes.
Get creative with the special object - I made a game where you dodge flowers while constantly growing for a mini jame gam. It got a lot of good votes. It's because of the storytelling, but I'd give you the advice of creativity.
Have a good story - Always think 2 days before making the game. If you already have a story in mind, let your imagination do the work FOR you.
Thats all I have, hope you have a good day and a good jam!