I look at the original, get a basic idea, then ask myself what about the picture is badly drawn, or I think looks bad or dumb. Usually it's small things, the way proportions look, things that are a bit big or small. Often, eyes will be drawn big, like in anime, so I make them bulbous, I'll make ears stupidly large Sometimes people draw their character in this smushed way, so I instead make them scrawny. Basically a caricature.