Best is if you learn how to pose on your own, and only rely on photographer or stylist/art director to give pointers, and not entire directions. Learn the basics, then do test shoots with pre-determined light set-ups to find out what works and doesn't work for you.
The two key problems with subjects here is that 1) They have no idea how to pose, what angles flatter their features, how to understand what lenses and light combinations work with what poses and angles and 2) they don't know how to emote and have extremely limited emotional vocabulary.
This is compounded by photographers who also do not understand the above, and how to communicate effectively with their subjects.
Which explains the very blah results you often see in P&P. :bsmilie: