Step 1 - Head Rough Thumbnail sketches

Step 2 - Line Drawing - I tried to simulate the poncing technique used by Michelangelo on the ceiling.  Notice the dots transferred from the reference image.  Then the final line drawing was done over the dots.  Conan's arm and hand was sketched without a reference

Step 3 - Background color painting in Photoshop.

Step 4 - Verdaccio painting of the forms.  The skin colors were "glazed" over this value painting. The start can be seen around the face.  Over painting to correct colors and add highlights was the final step.