My friend Judy sent me an article on illustrator Will Hillenbrand . He works in many different mediums and one of them uses colored pencil and markers on Clearprint Design Vellum. The neat thing about it is that you can print your sketch right onto the paper, here I've printed it on the backside, and you can work both sides of the paper. I created an underpainting on the sketch or back side using complementary colors that provide depth to the front drawing. I also discovered after purchasing several expensive Copic markers, that I could use the clear blender marker to smear the colored pencil, best seen in the blue and gray clouds. Another great thing is that the colored pencil erases pretty easily off the vellum, which helps me to stay loose. One drawback is that whites and light colors can only go so far, so I still have to do those value studies!