First off, don't overmix your pancake batter. This will develop the gluten in the flour and make your pancakes tough and pourous. Second, make sure your pan is at the right temperature. You definitely want it preheated before the pancake batter hits the pan. Test it by sprinkling a few drops of water into the pan. They should dance and sizzle across the pan. If they just lie there, the pan is too cold. If they evaporate immediately, it's too hot. Finally, be swift and decisive in your flipping. Bad flips tend to come from hesitation. Just go for it.