Hey, I didn't see this thread until...right this moment! Heheh. I saw the pictures when you posted them on Facebook though.
It looks great! A tablet definitely helps a LOT - you get pressure sensitivity and line variation, it's awesome.
It's probably silly to leave a critique here, but I think it would be helpful.
I would try to pick a light source, to help you "light" the hair and head - some areas in shadow, some areas in light. Right now, all of the hair has a very uniform light on it. For instance, the hair behind the right side of her face would probably be in shadow. Also, keeping some areas more detailed and some areas softened will add to the realism. That same area of hair would also probably be less detailed with maybe a few highlights.
This is an old old tutorial by Enayla, but I think it gives some great tips: