How to study openings

Study the basic rules of the opening. Then go on to each opening theory by buying a book.

In my opinion, you should pick a solid opening and play the same one with white every time, in all of your online games. It's overwhelming to attempt to learn a lot of variations in several different openings.

Experience is the best way to learn. Opponents will have tons of different responses to your opening line. Use tools like the Opening Explorer to determine what are good responses to these lines. If you run into a response that gives you a lot of trouble, post the game in the forums and find out what you should play when faced with that response.

After a while you will get pretty good with your opening of choice, and play it with confidence.

Where do you stand at the moment ?

- do you play OTB (rating ?) or only live chess ? which time-control ?

- do you already have a basic repertoire ? (ie. I play 1.e4, closed sicilian, Ruy Lopey, French against 1.e4...) or aren't you anywhere close to this point

- if you have a basic repertoire and some openings you feel comfortable with, then Estragon's advice to simply go through the games of a famous exponent is best - I would suggest to pick old games (before '85) -

- if you don't have any basic repertoire, then you need to create something from scratch - you can ask for advice in the forums or ask a coach to save time and choose wisely

- if you have a basic repertoire but feel uncomfortable everywhere, then go back to the previous step, though it may be a case of unsufficient grasp of the basics in opening play or tactics