If you're mostly making your game jam game for yourself then this doesn't apply, but if you're hoping a lot of fellow jammers will play and enjoy your game, here are some of my thoughts.

• People will be playing a lot of games, so any friction in getting to your game is going to be a problem.
• Make it run in the browser if at all possible (downloading and unzipping a file is just enough of a pain that people won't do it). Especially if there are tons of other games that do run in the browser.
• Make your game easy to understand. If your idea requires a tutorial to ease players into it, making that tutorial will take time away from making your actual game. People might not even be willing to go through a tutorial.
• Bold important words in your directions (like score and Gameover). This gives the viewer's eye something to latch on to so they might actually read your directions.
• Think about what assets are easy/hard to make. Text and voices can be produced rather quickly and can add a lot of content to your game. (We recorded 20 sounds that made it into the game in 1 hour)

https://ldjam.com/events/ludum-dare/42/camp-snuggle