When you draw the circle, add the exact half of the circle to it, as a base for the chin. You need to take a closer look at the 2/3 and 1/3 rules. You should keep the perspective rather easy until you understand the proportions correctly. Maybe my versions helps you [link] . I managed to work through the complete book last week and I'm still fascinated by it, he's such a great artist and teacher! Thanks again for pointing this great book out to me !
I think observing page 77 would help you a lot, that's the step where you mess up. Just get this basic form right before adding all the other features.
That's a great tip; so obvious once you point it out , especially on p77. Thanks! Will have to keep that in mind. While we're at it, do you have any tricks for determining how wide to make the head (sort of like where to cut off the sides of the cranial sphere from the frontal view, to make the side planes of the head)? That gives me tons of trouble, heh.