Practice, practice, practice.....and some formal education certainly could help put the pieces together for you. I have been doing digital art in one form or another for over ten years. A few years ago I got my degree in computer art and animation, with the greatest benefit for me coming from the design classes. I've since been working as an illustrator and art director. If you don't necessarily want to go for an entire degree program, you could always check with local community colleges to just take a class or two. Having said all that....the bottom line is get your skills as sharp as possible. All the education in the world is no substitute for talent.