The great thing about digital is that once you've bough the equipment, learning to shoot is cheap because they are no consumables.
Try going to your local library and checking out books on photography. The books from the film days will still be useful to the extent they discuss composition. Don't get bogged down in the technical details--at first, let the camera do the heavy lifting with regard to light metering and white balance--instead, concentrate on composition. My rule of thumb is simple: if it looks good, it is good. When you make a picture that looks good, remember how you did it and apply those same practices to subsequent pictures.
One key to taking good photographs also is found in target shooting: don't take a bad shot just to have taken a shot. If you're not happy with the composition in the viewfinder, move. If the light isn't good, wait. Try taking pictures from a kneeling or sitting position to introduce a new perspective. Take your zoom, set it at one focal length, and commit to taking pictures with only that focal length for an afternoon. When you get home, edit your pictures right away if you can so you can remember what you were doing when you shot the pictures you like. Try to learn something new each time you take the camera out.
For nature photography tips it is hard to beat Art Wolfe's books. "The New Art of Nature Photography" and "The Art of the Photograph" are both excellent books and relatively inexpensive. The best money I've ever spent on photography I spent on lenses, and on books. The more you look at good photographs, the better your own will become.
