For you artists and art fans out there, here's a terrific piece on
color studies. It explains what they are, how they work, and how to use them. If I need to color something, I can usually do the trick in my head, but for a major project I may well lay it out with color chips so I can make visual comparisons side-by-side. As an art fan, I
love the kind of color study where the artist lays out a bunch of variations of the same thing with different colors of background, foreground, subject, details such as clothes or flowers, etc.
In the River Valley set, you can see how the last three combinations work best. The yellow grass gives the most contrast, while the green is the most vibrant overall. There's no better way to learn the
application of color theory than to stand in front of such a set and discuss why you feel that certain choices worked or didn't work. For instance, the very orange frames would work if painting Australia, but the blue stream would need to be much brighter and probably have some green along its margins, because that's how things look in that setting. As is, it just kinda looks like someone popped a red filter over a camera lens. Similarly the grey ones could go for somewhere foggy like Scotland or California, but you'd probably need to add colorful details such as tiny pink wildflowers to keep it from being completely blah.