The structure is pretty good.
Here are a few things I think could be different: http://sta.sh/01s53td80jry
(Now that I look at your picture again, I see that there are eyes. I didn’t notice them at first.)
You could work more on the shading too. Establish a direction the light comes from and try to see the volumes. The head as a whole, the cheeks, lips, nose etc.
Most of the time, the light comes from above, so you usually get shadow under the nose and under the chin.
I did a quick test shading: http://sta.sh/0am161rf903
I hope you don’t mind these paint-overs. 