Relax. One of the major causes of a stiff appearance in photographs is a stiff bodily pose brought about by anxiety and nerves. Seek to remove the tension from your body using deep inhale and exhale exercises (if you're a Pilates, yoga, meditation, or martial arts devotee, you'll already know about doing deep breathing to relax). Shake your body around a little to loosen up; if you can't do this because of the clothing and makeup you're wearing, at least stretch and wriggle as much as you can. Visualize calm scenes in your mind and think peaceful, positive thoughts. The process before you is but one process in life, one of many, and you'll do just fine. Choose a focus point. It's important that you can center your viewpoint so that your eyes aren't darting about everywhere and creating a sense of being unsettled or uncertain. By selecting a focus point, you have somewhere to aim your look and steady your gaze. People and things to focus on include: the photographer, the camera, the person motivating you behind the photographer, an object at the right height where you've been asked to gaze, or an item of food you really would rather be eating.
Belinda