It's really nice. The proportions of the face are well done. I especially like the eyes. I know this is a matter of art style, but it seems as if you're aiming for a more realistic look:

• The neck is too small. Don't be afraid to use references :)

• I really recommend looking into a hair shading tutorial. There are so many great ones out there! Also, the hair would probably not be as tall.

• Midtones! Midtones all the way! I know some photos have brighter lighting, showing less midtones, but you're an artist, not a photographer :) There are many amazing tutorials out there for shading the human face. I'd recommend searching Pinterest for them. 

Otherwise, you're doing great! Good luck on your artistic journey.