To make a better basic structure, you need to apply more structure to the base
ClickStarted with the rough shape, though ended with the hat. The grey lines are potential `outlines` though what I really drew here was the grey sketch lines that display volume. Although it is traced from the photo, that makes it more clear what I drew; drawing on a smaller scale, only looking at the photo should not obstruct you from doing this.
I'm showing the relationship in shape. Started with the face, a big circle if you'd ask me! The nose, also a circle, a small tip - another circle - and nostril, again a circle; although having a hole in the end result.
I went on with the cheeks and chin, chin leading to the jaw, all of those leading to a proper mouth space. The eyes sockets are.. sort of circular, and I had a bit of a help circle above the left cheek. It probably would've bene better if I'd have considered the helpcircle and the other circle as one volume, same going for the other cheek.
Combining volumes and their relationships, attachments and overlap of structural elements, those build up your drawing in a proper way. It may require study of facial anatomy, though just looking at it's exterior topology may prove enough (I probably haven't studied even 1% of what I should've to be explaining you this properly though
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