prob sounds dumb kinda but i just took this sketch, removed saturation and colored under it with grays, merged them and made a color mask on top of it and added additional details on top
i also applied a gradient map but thats besides the point
idk its prob kind of a cheat method but i struggled a bit with stylized painting and doing an extra messy sketch helped a lot bc i could just turn my pen pressure opacity into the values bc im better at traditional stuff and it feels more traditionally logical to paint that way but idk i hate painting with actual paint so