For the most part when you are painting in SketchBook Pro, you are following the same rules and principals you would use with traditional media. There are slight differences and some advantages, but all in all, the computer is just another medium.
The following demonstrations will show how to develop a painting using SketchBook Pro. The steps used are almost exactly the same steps one would use in developing a painting using traditional materials. The exception is that one may take advantage of the tools available in SketchBook Pro. These tools include working on layers, controlling the opacity of the layers, the Lasso tool, as well as being able to use and/or create a vast array of brushes, and the ability to click on redo when you are unsatisfied with a result.
The first demonstration will be a simple subject relying on the layers and one brush to develop the image. The second demonstration will involve a more complicated composition and make use of more tools...