Asymmetry and depth. Remember "rule of thirds." Divide your frame into top third, middle, bottom, and/or left, middle, right. Depth can also be divided into thirds-- foreground, middle ground, background. Stand far away and max zoom on your subject to sharpen your subject against a softer focus background. Look for or create relationships between the elements of the photo. Have people touch or look at each other, but in a chain instead of in pairs. The photographer/viewer can be part of this chain. Also, shoot people with the camera at chest level, or choose a high or low angle for effect.