Had a class on inventing figures for animation by Rad Sechrist (Dreamworks) today. Here’s a few pages from my notes on breaking down head structure and tips on varying head sizes and shapes.  Some of these you might already know, but it’s still very useful to keep in mind while drawing.  

Also a tip on how to draw jawline when the character is looking upwards.  Most common mistake is in drawing the jawline facing at an angle above horizontal, because when heads look up, jawline is still either in line with the horizontal, or slightly below it.  The only time jawline point at an angle above horizon is when the character is looking up at an extreme angle (almost straight up!)