The reason why I am so enthusiastic about the photography of Henri Cartier Bresson, that is, my passion for Composition.
The first big thing — you must experiment. Take chances. Digital photography as superior to film photography for experimentation and risk taking.
Experiment with random and bold compositions. You might have to take 100 photos of the same scene to get one successful interesting and unique composition. Much of interesting composition — you discover it after the fact. You discover it during the image reviewing phase.