Good proportions overall but the materials need a huge amount of work, everything looks very artificial and plastic. The eyelashes are too soft & fuzzy, need to be a bit spikier (though this may be due to their shadows, which look odd to me); the eyebrows have good strand structure but the taper is backwards – they should be thicker toward the center of the brow and taper to the outside of their arc. The head hair is nicely done though the hairline where the strands enter looks a little abrupt. Think about making the transition from lower lip to upper chin area little less drastic (though softening the shadows may help this, also), to help the lip look softer and fleshier. The overall bone structure of the face is OK but lacks the small tweaks of detail that can really humanize a character. Hints of bone shapes under the cheekbones, brows, chin and bridge of the nose, even very subtle ones, can help a lot. Also make sure the nose isn’t too generic-looking, they are all unique and a little custom shaping there can create a more natural look. Add at least a suggestion of the naso-labial folds.
RE: Material & textures. Skin almost always needs an SSS material to work well, so look into the options for using that. You’ll also want bump maps for pores, blemishes, and lip wrinkles. Using Texture Paint to add subtle coloration details is a good way to liven up the skin – blush in the cheeks, a little paleness around the tip of the nose, lip coloration, etc. Plus freckles, moles, even a tiny zit or two Specular maps are important also, since not all areas of the face have the same “shininess.” The eyes need a suggestion of color – they are never pure white – and more definition of veins at the peripheries. Inner eyelid coloration should be pinker, and you can use a Shrinkwrap modifier to make the inner lid match up very close to the eyeball, and eliminate the gap. The transition from iris to sclera (the white part of the eyeball) is never hard-edged, so soften it some to lose that glass-eye look. Iris coloration looks pretty good if a bit too dark & contrasty.
All of the above is in the way of fine tuning what is already a very good start, depending on how far towards a naturalistic look you want to go.