How can I improve this?

Hi all. This is part of a project with my students. As I am not very good artist, can you tell me what things should I improve in the picture?
Thanks a lot.

Improve the red areas marked on the attached images.

Remove the outline where it shouldn’t be.
Give continuity to the hair on the sides of the head.
Give volume to the nose and mouth

Eyes look good so far to me!

Thanks a lot, genete. I continue with the same drawing. I still must improve his mouth, but I finished the body. The girl is sitting on a chair (a real one). What things should I improve?
(Forget the shoes, they are not visible in the scene.)