I have taken a coloring class with Kit and Clowder. I have been coloring my whole life-57 years! But their class taught me the right way to color. They teach you about casting shadows and regular shading. It has greatly improved my coloring! I hope you'll check her facebook page out.
The was a freebie offered during their 20 days of giveaways for reaching 20,000 followers. They must be doing something right!