Are you using references ? you could see where your off or where you have it nailed better like that. You have some of the basic anatomy details fine. its just there placement is off a bit. Forehead is not high enough. Jow line needs to be lower and out more. Eye's are to close to the eyebrows.
Kind of looks like your trying to go a little to low on the poly cage. You could add some edges in a edge loop fashion and it could help much.
Pony has a good point there, about the reference images.
I would like to add that your model is alot more round than a human head would be. A human head would be more like an oval or an egg. A lot taller then your head.
I also think that it seems like theres something wrong at the cheek area on your model.
A good tip when creating a head is to rough out the basic head shape first and when you are satisfied with the basic shape, and everything match up with your reference material then start on details like wrinkles, eyes etc.