Now to do the head. Here are the references I was given.
The book wanted me to use the method similar to what I did with Harvey awhile ago. This is where I see the smoothed version as I work while I'm really manipulating the boxy version underneath. I'm not sure if that makes sense to you. I'm not a huge fan of it because the boxy version can end up crazy looking since I'm not actually seeing it. Anyway, here's the general shape above.
So modeling mainly consists of extruding sections in and out while making them bigger or smaller, adding in more detail when needed and then tweaking things here and there. Here I pulled out some ears, pushed in the eye socket, pulled out the nose and pushed in the nostrils.
Next I created the mouth and refined the face more. I rotated the eye sockets so they face forward more. I also created the mouth cavity which was a little tricky. You can't see it but you'll see why I had to make it eventually. Finally, I modeled the glasses below. It'll be missing one lens.