I got into photography by joining
Deviant Art, looking at hundreds of photos and deciding which ones I liked, then determining what about those particular photos made them special and went out to emulate that. I think I'm lucky in that I have a good eye for composition, but exposing yourself to loads of good examples of the particular medium you like and reading about it in books, magazines and websites (for example, for photography I've read about the different settings on a camera and what they can do; for drawing or painting you could read about different materials and techniques etc) will put you in good stead. Also, just practice LOADS - it shoudn't be a chore. You should choose whatever it is you want to do because you find it fun.
