A little head sketch. Actually, it's just the beginning of a sketch. I didn't get very far because I was doing this in between my "rounds" during class, but I did manage to take shots of the process with my iPhone. (That is to say, sorry for the poor quality of the photos :-)
The first pic shows the basic darw-in. Pretty loose. I'm just trying to indicate the volume of the head mass (note the front and the side planes are differentiated) and place the features more or less where they should be.
And then I drew in the neck and what's visible of the upper torso. The little near-vertical line across the collar of her shirt indicates the center of the front of her torso, defines which way the torso is facing.
Roughly filling in the shadow areas. Sometimes I use washes. This time I used a more dry-brushy scrubby technique. Either way works. No particular reason why I used this method except whim.
Switching to opaque colors (up till now, it was transparent), I started in on the shadow side of the face. I'm still painting pretty dry, but noting three or four main variations all in the shadow side, and loosely indicating them.
I now filled in the lit side. Sometimes I start with the lit side, other times I start with the shadow side. I'm not sure what the deciding factor is, if there is one. This particular head was nearly back lit, so I decided to go really light in the light side, almost washed out. And the shadow side is also keyed up as well.
More paint and manipulating edges and transitions, adjusting anatomy and defining the center of interest. (the eye closest to us)
I got some paint in the background, and started defining the contour a bit from the outside. On her lit side I wanted to lose edges almost completely. The drawing started to get wonky but I ran out of time. I figured I'd just take it home and finish it up. Later I realized I didn't take a photo of the model. I tried to paint from memory, something I do often enough but this was a sort of a portrait treatment, which means I really needed accuracy. Without the model or a photo reference, it just got sloppy and too generic so...
I got a nicely toned canvas for another painting!