My drawing of Chris John Millington, a Scottish model based in New York
Today I met a watercolor artist while visiting a carnival. I learned two important things from him:
Subtlety
When I showed him the drawing above he immediately pointed out the technique I used to capture the model's fading haircut style. It's all bout the details. The dark areas would blend with the very light parts with a gradient. However I did vary how the fast the darks gradient into the whites (For example the gradient changes faster near the back of his head). Those details make for realism more precisely.
Making your drawing look convincing
In this case it's all about foreground, background. Making them 'work together', as he said, requires understanding of the subject and its surroundings, as well as the lighting involved. How I achieved this specifically is by completely merging the lightest parts on the his face with the background with absolutely no shading involved. The forehead for example, if backlit with bright natural light, should contain as little shading as possible. I avoid solid outlines as it would make the subject look out of place from its surroundings.