I just love the work of Charles Reid. He's not only an amazing artist, he's an excellent teacher. His books are always full of great, insightful advice. Right now I have two books checked out of the library, Watercolor Secrets and Portraits And Figures in Watercolor. Two of the best tips I got from these books is to 1) mix your paint on the paper, not on your palette and 2) keep your values simple, ie. don't put three different values in one shadow area. These are two things I can start doing right away. I can't wait to get started!