Every successful image is comprised of several key elements that define its character: exposure, the balance and movement of the composition, the interplay of tone and color. Focal point and depth of field are critical components as well.
Picking a focal point and highlighting it with shallow depth of field makes the subject “pop”,but one risks over-revealing. Sometime the eye has nothing to do except dwell on the primary subject. Watch people in a gallery. They pass by an over-simple image in moments while an interesting composition engages them for a while.