In this Coffee Break Course, digital artist Robert Marzullo will show you the step-by-step process of blending paint in Sketchbook Pro 8. You will learn three different methods of accomplishing this form of painting: how to blend with opacity, how to blend with the synthetic brushes, and how to blend with the soft airbrush.
http://design.tutsplus.com/courses/blending-techniques-in-sketchbook-pro-8
http://design.tutsplus.com/courses/blending-techniques-in-sketchbook-pro-8