Oil Painting Portrait Workshop at Victorian Artists Society - Day 6

This is the third painting at this workshop.
I'm reasonably happy with composition and likeliness of the subject, but, not happy with skin tones on this one.
I probably did too much simplification, not so much variations of tones, hence, the face looks very flat.
I'm really struggling with oil painting portrait. It's very challenging.

Oil on canvas. 14 x 16 in.