Hair is interesting, there is a fine line between it looking authentic or stringy.
I spent this session on the models left side with her hair, arm and breast. I’m not sure how authentic the hair is looking here, I may have to go over it again and smooth it out a bit more.
Normally hair is all together in one blocky sort of shape with fuzzy edges in a lot of places and a few sharp edges near the high lights. But this pose the models hair is scattered all over the place and you can clearly pick out many individual strands.
You could read in a lot of art books about treating hair as one blocky shape and not to paint each individual strand but in this case that simply will not work. I could generalize some of the shapes, but for the most part I had to paint strands of hair.
Sargent is a great example of generalizing shapes into broad strokes, or Sorolla, or Zorn, Schmid… Give me some time and I could make a long list of artists that do the same. But, you can’t generalize everything, if you’re painting a zebra, you will probably end up painting black stripes.