The portrait quest continues, and instead of profile portraits I'm now doing half-portraits, which are harder to measure. You create a line in the middle of the face, set up another to line up the eyes, and then start doing the contours, nose, hair, and so on.
I googled "half-profile portrait" or something like that and found YARIG (yet another random Internet girl) and got to drawing. The mouth, hair and nose are still tough, but it's great when I get something that I'm happy with. Somehow within just a few seconds the expression goes from looking dumb as a rock to something sort of, kind of realistic looking.