My first response would be not to worry about it too much because then, any tells you do give off - genuine, automatic tells - will probably be exaggerated.

If you're a beginner, you'll be playing with other beginners - they won't even notice, most likely. You can get to know your own tells by studying your opponents - what do they do that gives away their hand? Do you do any of the same things?

The best way to discipline yourself is to make sure your game is solid and consistent, you remain relatively sober and you concentrate on playing poker. Don't start relying on tells until you have enough experience playing live to be able to consistently recognise them, otherwise you'll start making bad plays based on hunches or misinformation.