Copying a master painting is a very useful exercise. Here is The Favorite Horse by John Singer Sargent. First make the “linear placement” — where the shapes go on the page. Then, start to think about how Sargent did this very warm and subtle painting.
This was a challenging assignment, not only because I haven’t been working in watercolor, but it is very difficult to reproduce the physical properties of wet watercolor. Although the copy is miles away from the brilliance of the original, copying this helped me to see the importance of relative values, and subtle things that occur when there are only small amounts of light.