Step 1, Block coloring areas with magic wand tools or by selecting those areas manually (for detail case).
Step 2, use main or primary color for the first layer (i named my layer with an alphabeth + numbering. Ex, Hair -> h-1 this can help us to continue our work after)
Step 3, Shade, with darker color, to make our work looks good be careful with putting shade with random angle.
Step 4, cleaning shades parts
Step 5, shades details with water color.
Here’s the results from shading, next is lighting.
Step, 6 Makes shadow or light by playing with layer effects. We can makes lighting with luminousity mode, and shadow with multiply mode.
Step 7, finishing, we can add some lighting line by new lineart page and also configure our shadows and lights perfectly by layers opacity.