Hopefully you have some nice, dark shadow colors now. You'll notice that Yori's hair still isn't completely black. I like to avoid 100% black because nothing is truly 100% black. There's color in everything, and I think avoiding total black adds a much richer feel to an image. Of course my linework is completely black so maybe I'm just a hypocrite.

On your layers palette, click on the layer mask button as shown. A layer thumbnail appears next to your shadows layer thumb. This is your layer mask, and it gives you complete control over your shadow layer's opacity. Now what you want is for your base colors to show through your shadow layer where you think light should be hitting your figure. If you want the tip of your character's nose to be light, the layer mask will let you do it.

I called this a cell style tutorial, but in truth, from this point on you can choose to continue this as either a cell or soft shaded piece. Simply make certain you have the Layer Mask selected on your shadow layer, and start painting with a black brush. whether it's soft or cell depends on the brush's hardness. If you make something too dark, you can take a white brush and lighten it up. With a layer mask you're not erasing your color, you're simply creating opacity holes that let the base color layer below shine through.

This is really my favorite part of the coloring process because it's what really calls upon your artistic knowledge of light and value changes.