Shading in CSP

I like to color in my character with the base colors instead of isolating the skin, working on that, and then moving onto the next section. If you start by filling in all the areas you can make sure the colors you chose go well with each other.

Only three colors are shown here, all about the same value. Because I make sure not to leave gaps in my lines I can use the fill bucket for my base colors, by creating a layer underneath my lineart layer, and selecting the "refer other layers" option on the fill bucket settings.

This allows the fill bucket to sense the lines on the lineart layer without having to actually color On that layer.

After selecting my colors, sometimes changing my initial choices, I add shadows. To give my characters a more "alive" and bright feeling, I try to use shadow colors that are deeper instead of darker.

For this guy I wanted a very warm color scheme, so both shadows and base colors have a lot of yellow in them.

And then I just touch up with some highlights! I use a LOT of shadows, but when it comes to highlights, more is less for me. So I just touched up his shoulders with a low-opacity yellow, and lightened up his hair with a light orange. 

To make his skin pop a little more I took the pencil tool and a orange red and lightly colored the tip of his nose, his elbows, and under his eyes.