Getting in close to your subject is one way to immediately add more impact to the photograph. Once you think you have gotten in as close as you should, try going in even closer. This is especially true for portraits, as seen above in the portrait of Kiki seemingly in deep thought. The framing only reveals her right eye and some of her head leaving all else a mystery to the viewer.
It helps to use a macro lens to make this kind of shot. Another good way is to use a long focal length (200mm+).
The get close, and then get closer composition style also works for group portraits, not just single subject portraits. In the above example showing the groom and groomsmen head to toe is a fine shot, but the viewer feels distant from the subject. Zooming in and composing a much tighter shot reveals each person's individual character more and makes for a much more personal experience for the viewer.
Try getting much closer than you normally do in composing your shots and let me know in the comments below what the results were.