After the sketch has been sprayed with fixative (an important step, otherwise the sketch will be destroyed by this phase!), I begin painting in the tones - light, middle and dark values - which will help me keep the depth of the painting throughout the process. Again, no details required at this point, they'll come later.
I've added just a hint of dulled-down color here, but the real goal of this step is getting those tones in. As I progress, the paint will be applied thicker and the true colors will be introduced.
The next step: Thicker paint!