If you are having difficulty holding your camera straight, purchase a tripod. A tripod will go a long way in helping to keep your camera in place, so you can focus on other variables other than balance. Tripods work great if you are in the wilderness or on an uneven terrain.
In most portrait photos, the subject's eyes look directly into the camera. Have your subject express a variety of emotions to capture a unique photograph. You could also try to have the people in the picture look at something in the frame.