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.

Maybe take a look at : https://www.caligraphics.dk/Maya/toonMe/toonMe.htm Maybe that can give you a pointer in the right direction, or atleast give you an idea of how I am working with CPS (I am not saying this is the right way, but it works for me)

Good luck, and im looking forward to see an update on your head