How do I direct stiff or difficult people in a photo shoot?

You can direct most subjects well now. It is the stiff ones and the difficult ones who still beat you. Here is what is really going on: stiffness is almost always nerves, and difficulty is often nerves wearing a harder mask. The person frozen in front of your lens is usually just uncomfortable and unsure what to do with their body. So your job with them is not better posing instructions. It is making them forget the camera. Talk to them like a person, give them something small and easy to do, get them laughing or moving before you get them posing. When the self-consciousness drops, the stiffness melts on its own. You are directing a mood, not a mannequin. With your next tricky subject, spend the first two minutes not shooting at all, just talking and putting them at ease. Warmth loosens people faster than any pose. Get the person comfortable and the picture will follow.