There are probably lots of things to consider. Only done two myself, but would say; dedicate time to brainstorming and planning, keep the game simple/small so you can finish it, prototype/build and test early, and go for a browser-based game to make it easy for people to play. Finally, I would recommend joining the discord server for the game jam. Usually, this is a good place to get help and encouragement. Hope that helps a bit!