Dark hair tutorial with SAI

My friends asked how I painted my hair, since I can't find a place that can host big images, I'll just post it here.
This was made for dark hairs that used the color Black as a base and went from there.
Although you can add a new layer above the base color for the color. Why new layer? You can play with the opacity to adjust to your liking.

I know it's pretty messy, I really wasn't planning on making a tutorial so it was kinda rushed.

This probably works with photoshop as well, but they don't have luminous layer mode for the highlight. Use screen or linear dodge instead.