https://www.youtube.com/watch?v=KFziBfvAFnM
-
No prototypes. Just make the game. Polish as you go. Don't depend on polish happening later. Always maintain constantly shippable code. (Large teams require more planning though.)
-
It's incredibly important that your game can always be run by your team. Bulletproof your engine by providing defaults (for input data) upon load failure.