Stepping back to observe at the progress of the color palette of my graphic medicine memoir. This is color pencil, ink, and digital rendering.
My recent process:
sketch a panel in non-photo blue pencil
scan it digitally
adjust the blue tone
adjust the black and white level to deepen the blue further
convert the blue to black and white
adjust the black and white levels again
fill areas with variations of 50% grey
The pencils that give me the feel and line I prefer are Staedtler non-photo blue pencils. I have tried others but every brand feels different when pressed against paper. These Staedtler pencil aren't too hard or too soft...but lean, for sure, on the soft side. Currently, the cost about $2.25 a piece.