
“I always rough out my compositions for my images first so I can get a feeling of the final image in my mind before starting any work on the piece. So here in Fig.01, I did my composition study, and then moved on to rendering the girl in the pencil sketch to achieve the 3D form of the figure. I continue to achieve a sense of the pose and structure of the figure, with both lines and shade, until I am ready to scan it in and work digitally.”
http://www.3dtotal.com/team/Tutorials_3/makingof_spray_it/spray_it_01.php