Each artist has his own drawing technique. I can draw a face, with almost no visible transitions, as in the photo. But, sometimes, the sharpness of character or internal content requires more expressiveness than the anatomical or photographic correctness of the image. It happened with these two portraits. “Portrait of Ali” and “Portrait of Elizabeth” In many ways similar to its dynamism and character. In their images there is a steel will and charisma, the inner content of the image.
As for technology, then, better than animation, I will not tell. Initially, the tone is inherent in the image. Neutral is chosen, which becomes the background. I read that many artists have a “white sheet fear”. This is when they look at the list and are afraid to proceed. I do not have this, but when the average tone is already lying, you clearly see the future picture.