1-Straight idea acording the theme "It should be max 2 hours, usually take less time, also aproach this step for preparing your project setup".
2-Direct development of the most basic form of the idea "Coding main gameplay, doing art.. etc".
3-Complish "Start / End" that idea "After you finished it, use the last time you have left to polish as many things as possible".
4-Prepare your game as soon as possible to have early players with you, this also will help you with feedback from others "You might have some time to play others early prototipes, while step 3, you can release the main version before the polish final one!"
5-The moment you feel stressed out.. Stop and Chill, watch a movie.. Play.. or do something different to think deeply about the problem. It works almost most of the times.
6-Celebrate!!! Finishing a game is a miracle that many devs would love to do, the more games you finish, the better you will get,
This are my honest tips! The ones that i use to finish my Jam games, also they work 100% fantastic in serious ones that includes team and money behind.