C&C per req:
1. Let me guess, you just read about the "Rule" of Thirds? Remember that it's only a guideline at best. When shooting portraits, the portratit orientation (Vertical) is usually best. Here you've got a great deal of unused space image left, and have cropped the subject off at the knees. Additionally, the subject requires fill light for proper exposure.
2. As per #1 for composition and lighting. Notice the severe 'racoon' eyes the girl has and the blown highlights on her crown. This is a result of shooting a backlit subject without supplemental lighting. A reflector, something as simple as a large piece of white posterboard would have helped a great deal.
Just my $00.02 worth - your mileage may vary.
~John