so, basically what i do is that i set the base color ,then stack a multiply and add layer on top.
With an Air brush i set the basic color of the shadows with the multiply layer then set the light color with the Add layer.
That should give you all the necessary values for the object you're rendering, so you just pick the values you think will fit more on a spot.
Never forget that you have to have a light source to choose where to put certain shadows.
Also there's that thing called bounce light, it's based off the color of a surface hit by light, but there's less light that hits the area where the light bounces to.
Light bounces a surface based on the transparency of the surface, the color of the surface and the the texture of the surface.
If the texture of an object hit by light is soft, the light will be more spread on the surface, if the texture is more leathery or like plastic , the light will be more concentrated.
Ik this is just bunch of useless informations but i hope it helps anyway.
if it's on paper tho, i won't be able to help you, because i'm not used to draw on paper.
Ask me if you need more explaination :)
