To help inhibit the formation of PCAs (Polycyclic Aromatic Hydrocarbons) and HCAs (Heterocyclic Amines), marinade meats for at least 3 hours prior to grilling. Marinades require four components to be effective: 

1. Acid to help tenderize meat (lemon juice, lime juice, orange juice, wine, yogurt, buttermilk, vinegar). Acid also helps change the acidity of the meat so PAHs and HCAs are less likely to form.
2. Pungent herbs for flavor (rosemary, garlic, lemon zest, oregano, sage, mint).
3. Oil for moisture.
4. Enough time to let the marinating process work.

Pro tip: Limit sugary marinades and barbecue sauces, which tend to encourage charring.