I recommend to visit the following websites too:
Lizzie Harper ( Botanical and Natural History Illustrator)
Andre Jute ( Best Seller Author and Painter)
Russ Stutler ( the demi god of urban sketching)
Matthew Mattingly ( great art by an all weather artist)
Brian van der Spuy ( artist and author)
Michael Daley‘s very informative website about restoration and conservation malpractices