Nice portrait! I particularly like how you did the eyebrows, and I am especially convinced by your modeling of the nose and lips.
I recommend for future work on it to pay more attention to the position of the eyes; it looks like they are clipping into the eyelids. And to consider more variation in/layering of all of the hair.
Additionally, I would paint maps for subsurface scattering(skin translucency) and for increased specular sheen on certain areas of the face, like the upper cheeks, nose, eyelids, lips and forehead, to further describe the surface texture.