A marinade will add flavor and tenderness to a chicken, or any other meat. Marinades usually consist of a liquid, or mixture of several liquids, and added spices. A marinade with vinegar and oil will break down the muscles and make the chicken tasty and tender. Chicken should marinate for several hours in order to penetrate the meat. You can marinate chicken in the fridge for a couple of days before you cook it, even longer if it came out of the freezer.