This image below is a simple picture drawn using 9 values of the same colour. I wanted to show how easy it is to obtain atmospheric perspective by just painting using colour values. I completed a video tutorial on this topic mostly for application to digital art, which is here. Make sure you watch the totorial in HD. As indicated by Richard Robinson, the value-based painting concept is the key to successful oil painting as well. I do all my digital and oil paintings using the value-based colour concept. I bought his Mastering Colour course and it unlocked all the secrets of effective colour use and the value-based painting strategy to me.
Francois' Art Blog 