DanielK said:Those are good concepts to begin with. Also consider color as a compositional tool. Complimentary colors can direct the eye just as well as contrast.
Also, in a more advanced way, think of primary, secondary and tertiary subjects. See if you can get the eye to go from one to the next and the next and back to the primary. Easier said than done, but I think of composition as a means to control the viewers eye.
Daniel