Really good start..... nice clean geometry...
Only thing I would say is watch the faces around the mouth.
You should be able to get the faces going in a circular pattern, with out changing any thing major. This will help if your planning on using blendshapes.
Looking forward to updates...
Kurt
I am enough of an artist to draw freely upon my imagination, knowledge is limited, imagination encircles the world. (Albert Einstein)
https://www.artstation.com/kurtb