Hello! I hope I don't bother you by asking but could you (please!) describe how you draw the skin, please? (do you just the grey tones and some ... points afterwards or is there any special technique?
Hi, thanks for your question. There is no special technique or special tools I use, is just regular shading. Except that the paper I use is Bristol smooth or vellum. Then at times I use a soft tissue, like the Kleenex brand, and softly blend the tones with it to avoid having any pencil strokes visible. This is done several times with layers upon layers until the tones look right 
thank you very much! can I ask you something else... while drawing do you wear gloves or use some kind of underlay to prevent your drawing from getting dirty?
No gloves, but I do place blank sheets of white paper underneath my hands and arms to prevent smudging
ok, thank you 