Pencil and Paper
The process began with the outlines, or as I like to call it, "establishing the placements".
Proceeding that is defining the contrast, where the refinement of light and dark begins.
Shading is all about the visual loud and silent details that cause this to be the most lengthy step.
After shading come the values of tone that I refer to as "additives".
You then begin to develop layers of multiplied shadows and highlights.
The final step is to connect the elements. These elements are the facial features that are unique to each person.
After refining all of the detail, you are left with a wondrous work of art.
The process for doing anything should be in a constant state of improvement.