The trick is to do cellshade it, select all on a alpha locked duplicate layer and blur the imperfections out of it. And then if you are crazy like me, repeat this process on every clean surface for every light and shadow, and after 3 hours of doing it, overpaint every shining spot and AO shadows.
I’ve always been quick with color because of how quickly I go full ADHD gremlin by the time I’m painting, lol. If you look at the work I paint, you can tell when and where the ADHD flairs up, because there’s always a spot or two that’s oddly unpolished, lol.
Or you can just fuck around painting it by hand... honestly I don't even know how I do stuff, I just go: -this shit looks rough, let's polish -this is boring, need boob -silhouette go brrr -30 overpaint layers because I messed up perspective -(swearing in spanish) -Stain on screen or wrong layer?