I need to stress this is not a tutorial, but rather more of a walkthrough. I do not claim that my method or approach is correct. Also, these printscreens were made a long time ago. I have changed the way I CG since, especially in laying out skintones.

I always start with the skin. The skin generally sets the mood of the picture I'm going to paint. I select a color which will basically be the base tone. But don't listen to me, the pictures always come out looking like none of the colors I chose in the beginning. :p

I slap the color on. Don't worry with the colors outside the borders as they could be erased with the Wet Eraser later.

Then I slap on the shadows. I know beforehand that I want her skin to be reddish and tanned. Looks icky, no? Resist the urge to erase the excess outside-the-lines paint. S'not time for that yet.

Now to put on the highlight to the picture. I do this either by using the Wet Eraser, or by painting on a high-opacity light tone. For this picture, I used the Wet Eraser.

I'm just erasing the paint where I think the light's gonna hit. Light direction should be consistent and realistic. I want the picture to be dramatic, hence the harshly contrasting tones. You might want to select a softer look and choose less contrasting tones instead.