I am reading Juliette Aristides' book "Classical Drawing Atelier" right now, and two ideas jumped out at me that I kept in my mind while drawing this week:
Juliette points out that if you see a very blurry black & white photo of a family member, you will easily recognise the person. She makes the point that it's the big shapes that make a true likeness, not the "infinite minutiae" as she puts it.
The other idea was a quote she attributes to John Berger: "Strangely, you can tell whether a likeness is in a drawing or not when you've never set eyes on the model." I think it's true somehow: an inaccurate portrait may look human, but it is not convincing.
With these two ideas high in my mind, I was determined this week to do what it took to get a likeness of the model. Again, I wiped down a lot of a charcoal and re-analyzed all the features and their relationships.
I raised the chin and made the lips a bit fuller. I repositioned the ear significantly, which had a huge effect on the shape of the cheek on the light side. I think it is a better likeness.
One more 4-hour session to finish it up!