Hairstyles

I do agree that the attention grabbing element of this artwork is the flow in the hair. The correct use of highlights and Grayish tones; the end effect being not too contrasting and not otherwise, it is infact balanced in terms of contrast; giving the viewer a very realistic impression of hair. I do love the fact that how you experimented with folds and knots, and I do say that this will also serve as a great reference for other deviants out there who want to draw better hair.
You have achieved volume with less pencil strokes.
The only part that in my opionion only that would make it better is that if rather than leaving the ends of the hair with 'thick lines', why not make them fade away? ( as in lower the pressure on the pencil at the ends of the hair).

So concluding, I would say that this is infact a very beautiful piece of art, and I shall look forward to seeing more your art