Preheat your skillet first to medium heat and then add your oil. You can check if your skillet is hot enough by dropping a splash of water into the skillet, if it sizzles it is ready. Swirl oil in skillet, then add your burgers. Alternately, spray or rub grill grates with oil before preheating. Cook undisturbed for 4-5 minutes before flipping. They should release easily from the pan or grill.