for no tutorials - big props. you have a nice eye for detail. As to improving it, you'll want to look up 2 main things - edge loop patterns for faces, and study a bit of human anatomy. regardless of what kinda of detail you want (super realistic or toony) these two concepts will apply.
You did a decent job on the hair, but so far as 3d hair goes, my best advice is to look at a lot of professional 3d models for reference on how its done. I've found S-E to have particularly nice work in regards to hair, such as in crisis core, and (only notable one i can think of in ff12 - fran).
keep up the great work! nice to see more artists about here.
