Don't overwork the meat mixture, just mix it until the ingredients are incorporated. Keep in mind that adding extra ingredients like onions, peppers, and cheese can make it harder for the meat to bind together. When forming the patties, press all of the ingredients together firmly. Make sure your grill or pan is hot before adding the patties. Getting a nice sear right off the bat will help the patties hold their shape. Avoid flipping the burgers more than once. Constantly flipping them can cause them to rip apart.