The best thing you can do, really, is ride. The more you're on the bike, the more skill and comfort you'll develop. As the cliche goes, practice makes perfect.

I agree with im4smiley, too, that education can help to speed up the process. Sheldon Brown's site is a great spot to get tips that you can put into use in your practice, as are mags like Bicycling or various books on riding technique. Knowledge + practice = comfort = more fun!