One thing I emphasize over and over again at Watercolor College is the importance of tone (light vs dark).  In the course we focus heavily on mastering tonal control because it is tone that is the heart and soul of representational painting.

 In fact, you can learn a lot by looking at paintings that have been changed to greyscale (all of the color removed).  A greyscale version of the painting shows only the tonal structure.  If a painting reads nicely in greyscale, then that means its tonal structure is sound.  That means the painting will most likely be strong and successful.

 I have presented a sequence of images below that illustrate how a painting is really built by building the tonal structure.  This sequence also demonstrates that color is far less important than tone when it comes to representational, realistic painting.  The sequence of images shows a commissioned painting I did in progressive steps as the tonal structure slowly builds.  The end product is a highly realistic dog portrait.

I have changed all of the images to greyscale so that you can focus solely on the tonal structure, without the distraction of color.  But, just because I know you are curious, I've also included the completed painting in color.