This is probably going to sound harsh, but here goes:
- The image is under-exposed. The skin tones are off and it looks like your model has got grey skin. A pop of fill flash would have rectified this, added life to the eyes and brought out the colour of the grass more.
- The posing is poor. The legs apart, leaning forward might work well for showing off her boobs, but it also makes it look like she's riding an invisible horse. Her arms are doing nothing - they're just hanging there, and as a result the body is roughly composed of two triangles (via the arms and the legs), which make don't do anything flattering for her body shape.
- Her head position could be better - she's square on to the camera which means there is very little separation between her chin and her neck because it's not been lit. She's neither smiling nor serious - it's just a half-open mouth, which again does her no favours. Her eyes are just dead. Moving her head to the side slightly and dropping the chin a touch would help here.
- The fact that her dress has ridden up with the pose that she's in, makes it look like she's going to the loo...