multiply color layer

someone asked about this, putting it up just in case someone else didnt understand.

this is what the layers would look like here--->>>>

the part where im talking about shading.
put the layer on "multiply"

EDiT:
OH- and the same goes for the highlights( white on overlay)..i put it on top of my lines and flats


^{this screenshot was taken in photoshop but SAI also has the option to multipy layers which i use also...}


(oh and this is just one of the commissions i'm working on..character is not mine)