Some related reading, for those who want to dive in:
Hawthorne on Painting. A slim, small volume made up largely of notes culled from his students' notebooks. (Some of the notes will seem cryptic if you don't have at least an introductory knowledge of this Cape Cod School painting tradition, but they will nonetheless provoke your thinking about what it means to see and paint color in light.)
(An aside: At the time I'm posting this, Amazon tries to make a deal with you to purchase in conjunction another artist-of-the-past John F. Carlson's
Carlson's Guide to Landscape Painting. If you don't have this book and you don't take advantage of this opportunity, then in the words of Freud and Jung, "Yer nuts!")
The block painting exercises Mari mentions are graphically depicted and explained in Lois Griffel's
Painting the Impressionist Landscape. Director and instructor at the Cape Cod School of Art, Griffel is very much in the Hawthorne/Hensche lineage. It may interest some Forum members to know that, when an artist here is having trouble with value or color (often having apparently "missed" those lessons), it's not uncommon to hear the comment, "S/he needs to go back and do some block studies."
Peggy B. could write her own book on these folks.