Completely thaw meat and poultry before grilling so it cooks more evenly. Some recipes state to marinate meat and poultry for several hours or days, either to tenderize or add flavor. Always marinate food in the refrigerator, not on the counter. If some of the marinade is to be used as a sauce on the cooked food, save a portion of the marinade and don't put raw meat and poultry in it. And don't re-use the marinade used on raw meat and poultry unless it's boiled first to destroy any bacteria.
Some people like to cook food partially in the microwave, oven or stove to reduce grilling time.
Pre-cook immediately before grilling to destroy bacteria. And have the grill hot and ready to go. Keep Cold Foods Cold. When carrying food to a picnic site, keep it cold to minimize bacterial growth. Pack food right from the refrigerator into the cooler immediately before leaving home.