I hope you don't mind but I did a little bit of photoshop wiork on this image to show you what can be done with a basic image. Your comp was ok to start with it just needed a bit of touch up.
The pose is cute but only if this was a snap shot. Whatever is behind her is very distracting and needs to be removed.
The main problem I see with your work is the lighting, you really need to either make or buy a reflector to help fill in the shadows and make your models look more natural. Also be very aware of the background, look through the viewfinder and walk around the person to find the best shot. Trees in the background don?t usually work as they tend to distract and overpower the model. Try and find very natural settings, flowers, a bench, a pond... stuff like that.