Jo is an excellent artist and teacher and unlike all other instructors, he gives you the golden nuggets, or secrets that only the top professional artists know. He focuses on abstract shapes or interesting shapes and color values and gradation and harmonizing.
I encourage you to sign up for wetcanvas and read the threads posted there to give you an idea of what other artists have to say. http://www.wetcanvas.com/forums/showthread.php?t=778261&page=12&highlight=landscape+clyde+aspevig
There's a lot of useful information in those threads. I have them bookmarked.