Today I mixed a color close to local color and sponged on a few layers. Then came shadows with raw umber green, working with extremely thin layers. Finally, I felt I was on the right track!
And here a few hours later and with various very light pigment mixes, there is some modeling taking shape. I've had to scumble back a few times when I became a bit heavy handed with my mixes, particularly in the shadows.
Along with this new approach, I'm backing up my painting with readings from "Drawing The Head" by William L. Maughan and "Portrait Painting Atelier" by Suzanne Brooker. These are both awesome books.
I've also tossed the laptop and printouts for reference, working only from the Tashchen book. The images are larger, more detailed, and nicely colored.
I have been struggling, perhaps grumbling and whining, but all the while looking for solutions. I think I am finally moving onto a good process!