I use butter in a 7" non-stick skillet. I add all the other ingredients, like mushrooms, peppers, onions, etc....to get them softened. Then, I add two or three beaten eggs. With a rubber spatula, I lift the edges so the raw egg will run under the cooked egg. Do this till it's almost set. Then, with a circular motion I get the whole mass moving, to ensure that nothing is sticking on the bottom. Then, push you're hand away, dipping the pan enough for the eggs to slip over the side. It's a push away, push up sort of motion. Pull your hand back, lowering the pan as you do so, and catch the omelet as it falls back. Add cheese down the middle and cook for another 30 seconds. Let it slide out of the pan onto a plate using the side of the pan to fold it in half over the cheese, which will now be in the center.
It takes practice and a very good eye. Make sure your pan is hot enough and it's in good enough condition to not have anything stick.
How can we sleep while our beds are burning???