Milk is optional. I use a bit more than you do. An 8-10" thick bottomed shallow pan is traditional. You want the pan to get medium-high hot, then melt about 1 tbs of butter (olive oil can be used as well. Veggie oils and shortening don't work as well).
The secret to a fluffy omelet is getting air into the mixture. You don't need a blender- a wire whisk works well. Beat the eggs, then let them sit for 5-10 minutes to warm up. When they lose their chill, they'll hold more air and then you can whip them up again. The more bubbles you make the better.
You need to make omelets in a sequence:
-Melt butter-heat oil (be sure to get sides of pan).
-Butter is ready when a drop of water sizzles. Be careful that your pan isn't TOO hot- the butter will turn brown!
- Add fillings to the pan and sauté them for a minute or so. Meats and veggies should be chopped. Onions and green peppers need a little more time than ham or bacon, so add accordingly.
- Add eggs to the pan, then use a spatula to break bubbles/fill in bare spots. Your nearly done when the eggs are semi-runny but have a solid base. At this point add your cheese to 1/2 of the omelet.
- Flip the omelet in half with your spatula. The bottom should look a bit browned. Cover the pan for a few seconds, then the tricky part: uncover and flip! Omelet flipping takes practice- start small!
-Cover for a few more moments and serve. I've made hundreds of these in a hotel in my catering days!