I've never started with black gesso before, so this was an experiment...I sketched with a white colored pencil.
Then I blocked in colors with paints. I didn't know if the color would show up on the black, or allow too much black through, but I like what happened! The pink paint is a Liquitex Basics, and the white and reds are Golden Fluid Acrylics.
I just kind of blocked in shadows and highlights, keeping it loose.
Then I got out the Pitt pen and did some sketching details and defining edges. Added some highlights and little dots with the Sharpie water based pen.