Yesterday I tried another drawing technique to be able to shorten the drawing time. It is also one of the most difficult method that is used by artists with long practice, which is not my case :)
I was afraid I will completely mess up everything, but finally, I managed to finish the drawing within 3 hours. Of course with some mistakes, that will be corrected, probably, after I will make over 100 drawings like this one.
First, I draw the grey tones all over using vine charcoal. Then, I start directly to draw without any measurement, everything being checked by eye. It was faster until I get to hair which I draw it several times and actually took me more than a 1/3 of the time.
Some info related to materials used: A4 watercolor paper 200 gr, vine charcoal, charcoal pencils (hard, soft and ultra soft), graphite technical pencil, blending stumb and a lot of patience :)
I will also need to find a way to scan better the drawings as all of them seem harsh after scanning compare to live ones.