I always struggled with keeping the head "in place" when changing angles. But the cirlce and triangle method fixed that pretty fast. The key was using the circle to define the skull and the triangle to guide the direction of the jaw/chin BEFORE worrying about details (eyes, nose...)

Before, I'd try to eyeball everything.

Nailing the basic structure first made it easier to adjust the perspective!

I did two rough sketches in different poses in angles that always gave me trouble, a lineart and then a colored version to finish it off.

#XPPenTutorialPractice