back in the day, when I was in photography school, our portraiture teacher had us put together a pose book of stuff we took out of magazines etc. After teaching us the basics of composition, posing, etc, He told us to copy the poses at first, and gradually our own style would emerge. It was absolutely true. So I wouldn't worry about the fact that you are "copying". Read all you can on the topic of posing, and then put together a book of poses. It will go a long way towards keeping YOU calm during your sittings, and that will serve your clients well. Just be confident and take charge when directing your subjects and don't worry that you are copying someone else's poses. Your own style will eventually emerge as you become comfortable and begin to accept or reject their esthetic and develop your own. If you are still copying others after a year of doing a lot of sittings, throw the book away, you were an exception and that learning technique didn't work for you. For now, don't worry about it, copy away.