I like how you've done the curly hair.
On the face:
Lighting is inconsistent.
Facial structure is not quite right. Mouth is on the side of the head, features are misaligned. I recommend using some references to figure out the relative positions of the features. No time for an edit, but this might get you started:
Noses are larger than your brain likes to remember. Nostrils are often visible. The mouth should be closer to the long line of the cheek. The ear (and the lines in the hair above the ear) need to tilt with the head. The base of the nose and the upper lip should tilt a bit.
Strong light from above and to the side of a tilted head will highlight the outer edge of the eye socket, and then on to either the top or center of the cheek bone (depending on angles).
Pixeling a head with a tilt and a twist can be a bit tough, but you're working at a good size for it.
Good luck, keep at it.
Tourist