Hello ! It’s great ! I get the feeling that some extra improvements are needed in little places but I’m not advanced enough to point them with confidence.
I highly recommend you to take the time to read through this topic : Human Progress
I’m sure you’ll find it quite informative !
There is also that course, that I would take if I were serious with that :
https://cgcookie.com/courses/human-realistic-portrait-creation-with-blender
That said :
The face hairs seems quite dense, it works from a distance, but it seems a bit exaggerated to me, did you follow a reference for that ?
And for the SSS, it’s probably possible to find some tutorials online. There are different approach to skin, some people do a lot of refinement there by using different layers for blood vessels under the skin and stuff like that.
But it can already give nice results in it’s simplest form, it’s subtle anyway, or your character will look waxy rather that plasticy.