I'm a big fan of Ryan Putnam and was inspired by his avatar series to create my own avatar.
I started by doing an analysis of my face, translated that to sketches, and refined in Illustrator.
Keeping it simple was my goal. I'd study my face and takes simplistic notes on the arch of my eyebrows, square chin, triangular jaw, small ears, and tapered hair.
Afterwards, I'd translate my notes into simple shapes.