After having difficulty making professional looking omelettes I finally turned to good old Facebook again. The following recipe was created with advice from Diana.
She says, the most common mistake people make, when making omelettes is to add milk. There should be NO MILK, just water. Milk, according to Diana, is for scrambled eggs.
Beat eggs together with a very small amount of water (not milk.).
Add your spices, herbs etc.
Pour mixture into hot frying pan with either melted butter, a little oil or oil spray.
Once the edges start to bubble, put your filling (cheese, onions, mushrooms or whatever) in only HALF of the top of the omelette.
Then fold your other half over the top. So it looks like a half circle!