In my experience, eyes are rather tricky things to paint—and as small as they are in comparison to the rest of the face, they carry a huge amount of importance in a portrait. Not only do eyes need to look realistic, engaging, and alive, but they also need to resemble the eyes of the person that you’re painting.
In the following video, Craig Nelson demonstrates his own step-by-step methods for painting eyes, starting with the whites of the eyes in shadow, then moving on to the lash line, eyebrows, and folds of the upper eyelids before ever putting any color in the iris. More importantly, he’s getting the results below by continually studying his subject while painting. Take a look: