I have developed respect and appreciation for short order cooks. Making a passable omelette is not as easy as you think. If you have a personality type that strives for perfection, you may want to eat granola for breakfast. Mistakes will inevitably be made when making omelettes. What's great is that they can turn into a scramble or frittata and still be tasty.
Have a good 10-12 inch nonstick skillet.
Use two eggs for a one person omelette and three eggs for two if you fill it with lots of good things.
Don't use more than three eggs or the top won't cook before the bottom gets too brown.
If you have a big family, make multiple smaller omelettes.
Egg substitute can work but it's dicey. Any attempt I made always seemed to stick more than real eggs.
Cooking spray worked better than butter or olive oil and conferred less fat.
Even if you are on a reduced cholesterol diet, a couple of eggs on special occasions is reasonable.
The possibilities for fillings are endless. If you think a veggie needs to be cooked first, like red peppers, jalapenos, onions, mushrooms, etc., saute them before you cook the omelette and set aside. (I haven't figured out how to do the little thing over the "e" in saute or over the "n" in jalapeno on this website yet). Additions like diced tomatoes, cheese, and parsley can be added at the last minute uncooked.
Check out your favorite recipe sites on the net to find ideas for fillings.