Re: DSLR Cameras
One tip from this very amateur photographer.
Learn how to shoot manually. Turn off all the automated settings on your camera (after you've had a play, of course) and learn how to adjust aperture, focal length, exposure, etc. This will give you a much better understanding of what is actually going on when you take a picture and align you with the principles to produce better automated shots. Unlike with film, you get instant feedback with what you're doing. It's much easier to learn now that it was even fifteen years ago - speaking from experience.
Not denigrating automation at all but I only own one camera with automated features. It's not easy to produce good shots without them (which is why I'm still on a steep learning curve) but I feel as though I understand what I'm doing even if it will only improve through practice. Automation is there to help you but you shouldn't be using it for everything all of the time. With these modern DSLRs, it's quite possible to pick and choose which settings you want to be manual and use these to great effect.