initially i wasn't going to upload this because it seems repetitive, but i felt it showed the difference pretty well. you can see how flat things start out. just a bit of a hue shift for light and dark on each side, then a highlight. it turns out shading flat surfaces is different than round ones, and seems to be harder for me to wrap my head around.

i decided to shake things up and draw a shaded arm... but i was too afraid to make it skin colored so i just used black and pretended it was some rubber.. latex.. thing. lol. i really should have put more effort into the proportions, but this was a shading experiment. hopefully to others this makes it clearer how i got from the base color to the shaded bit. maybe make it click in someones head. otherwise, it's just for the record.

i will get there eventually...