Here is a three image Work in Progress sequence of this painting:
From above downwards : I began cursorily by pegging the perimeter of the figure, directly using brush and some ivory black (which was left over on my palette from an earlier session). I located the extremities e.g. top of head, right elbow, right shoulder, right toe, right knee, left toe, left knee, left shoulder (in that sequence) by points, and joined these to make a rough polygon. The figure was to be contained within this perimeter. Having drawn the figure, directly with brush, I made some sketchy tonal studies to glean info on the values.
Then I began to add color (although my original intention was to make this black and white), mostly burnt sienna, mixed with black or white, to get the tonal differences. I did use burnt umber here and there, but not much. Having roughly painted all over with this approach, I used a finer brush to adjust the details e.g. highlights, creases etc.
Reference by kind courtesy of GlamourPhotoLight in Deviantart.