Here's a tutorial on adding some color and value to a sketch to get a quick rendering. The video is actual time so without concentrating on talking and explaining this should take no more than 10min to add Photoshop. (Sketch approx 5min) This is a great way to express your sketches in a little more depth and prepare some variations for a final presentation rendering. This was a request by a reader so I hope it helps! Also please leave comments on any tricks you all may have when adding color quickly in Photoshop.
This technique is going from a thumbnail (approx 1inch) to a loose rendering. I will do another tutorial using a tighter sketch and then an in depth "photo realistic" rendering. So please check back!