It's not necessarily that they look forced as if you placed her...they look awkward...let her just walk to the tree and tell her to freeze then move her face so that you can adjust accordingly. It also looks better when you move around the model instead of the model moving around you.
Also, I don't know if this will sound right, but I was taught that you have Masculine and Feminine lighting/posing. You don't ever want a girl's shoulders straight toward you b/c she will look more butch where a guy would want to look like that. Same thing with the head. The little tilts and turns matter. So in the same picture have her tilt to the left and then the right and turn this way and that way and get 10 diff images all due to her head movement. THen pick what you like and erase the rest.
