agreed, i would change her pose. it's up to the photographer to position the model.
play around with different framing and aperture. say, close in a little to cut out some of the space (and that grey stuff hanging off the branches in top right corner) above her and soften the background with higher fstop
check out
a lot of useful reading on classic portraits http://www.thephotoforum.com/forum/articles-interest/268210-guide-classic-portraiture.html
you know the rule of thirds so consider this as well The Golden Ratio Photographers Composition Guide