Not sure about the art. There are many tutorials for computer based drawing/art which you can find at gamedev.net. My 2D art improved from hopeless to 'not so hopeless' when I bought a drawing tablet. In addition, get to know the graphics package you're using. If you are taking textures from photos then there is a great book called "The Dark Side of Game Texturing" by David Franson. You might also like "Game Art for Teens" by Les Pardew.
Hope it helps...
P.S. When did 'Teen' replace 'Beginner' in book titles? Very annoying.
Hope it helps...
P.S. When did 'Teen' replace 'Beginner' in book titles? Very annoying.