Marinating can add a world of flavor to the meats you cook, but you have to be very careful about how you go about it. Your marinade should always be refrigerated to below 40° F, or bacterial growth will begin. If bacteria run wild in your food, you may end up with food poisoning.
Want to keep eggs from spreading out when you poach them? Just add a little vinegar or lemon juice to the water you're cooking them in. The acid in the juice or vinegar helps the protein in the eggs to coagulate, which means they'll keep a tidy, rounded shape as they cook.