You could always try the traditional way: copy pictures. (I don't mean copy and pass off as your own, of course.) Choose a picture, study it for a while (5 or 10 minutes, perhaps more), ask yourself why it works and what it is that appeals to you, then make your own version. Repeat.
Originally Posted by stradibarrius
At some point you'll find that you prefer your versions to the originals, and you'll find your own style emerging. (Don't be disheartened if you don't reach this place for a while.) When you start to feel that you're exploring something important then repeat the exercise, but using your pictures as the starting point.
Don't limit yourself to photographs as inspiration. Look at some paintings or sculptures. Look at architecture and design. Look at the people around you. Look at clouds (Stieglitz's Equivalents). Do something daring that pushes you right outside your comfort zone. Stop listening to people who say that you're doing it wrong - if it feels right to you then it's right. Keep exploring.