1. Food stays in the belly.
2. Poops stay in the diaper.
Those are the two cardinal, hard and fast laws, but, here are some Strong Suggestions:
1. Focus only on eating. Babies don't need to multitask.
2. If it's light around you after you eat, stay awake and play.
3. If it's dark around you after you eat, go to sleep.
4. Suck a plug, even if you don't want to.