For the composition it would definitely look better if there was any perspective or some more interesting background and generally depth. For the hair I would first study what it exactly looks like, to know its exact shape and direction, try first doing it with pencil, play with values and then add colors. Hope it helps!
#Help with back view, especially hair and composition
low sky
low sky
Still water is good. Perspective, changing position of the "camera", but it is hard and you would need to change the whole painting so yeah, leave that for next paintings. What this painting surely lacks is values! It looks very flat. So try doing that first.
Do you have reference for this painting?