Not a bad start. You appear to be working in direct sun here. Sometimes that's unavoidable, but if possible it's usu rally better to shoot in open shade. Several problems pop up in direct sun. With the sun straight on like it is here, the lighting is really flat and provides no modeling of the models face. This can cause the face to appear wider then if parts of the face were in shadow. If the sun is coming in at an angle, then you have shadows that are much to dark for the camera sensor to deal with. If you can try shooting in open shade with a reflector or small off camera fill flash to pop some light back in, I think you will like the results.
Shot in open shade with reflector for fill.