If you're just starting out with digital painting, this is the series I would recommend.
Do you ever feel like you painting is too 'flat'? To create an illusion of 3D space on a flat canvas you must first understand form, light, and shadow. This 13 part series introduces the process of basic grayscale rendering in Photoshop. Beginning with the (included) pencil drawing, the videos guide you through the process of painting a basic object lit with a spotlight. Though the vase painted in this series is simple, the principles are fundamental and can be applied to more complex subject-matter.
Runtime: 45 Minutes (Digital Download)
Videos
1. Intro
2. Keyboard Commands
3. Canvas Prep
4. Shadow Shape
5. Illuminated Area
6. Reflected Light
7. Occlusion Shadows
8. Mistakes
9. Polish
10. Prepare to Refine
11. Refining the Vase
12. Finishing the Background
13. Post Processing