I have made one other game for a game jam, but I attempted to make another one way before that. It failed because I tried to submit it on the deadline and due to errors with memory, it wouldn't work. My biggest piece of advice is to check that your game works on itch.io every once in a while to see if there are any major bugs. Also, write out before you start what you want to add to the game, so you can scope out a rough 'schedule' and make sure that you can achieve everything in a month. One last piece of advice: if all else fails and the game can't be submitted (worst case scenario, I know) continue to work on the game if you have time, and maybe you can publish it yourself on your own time.