I don't remember if I've mentioned James Gurney before. He is both a realist painter and an illustrator/concept artist. If you have kids who love dinosaurs, you may have seen his book, Dinotopia.
Link to Gurney's blog: http://gurneyjourney.blogspot.ca/ Lots to explore here!
A recent post on Lines and Colors described Gurney's Fantasy in the Wild vid and provided a link to an earlier discussion and many pics of Gurney's Watercolor in the Wild (downloadable vid):
Definitely worth a look if you would like some tips on using watercolor "en plein air."
His book Color and Light is worth looking at as well: http://jamesgurney.com/site/213/color-and-light-a-guide-for-the-realist-painter