Along with some very good friends that I've met at our local camera club, and all the learning that goes on both on the program and judging nights, we sometimes have very special presenters. Tonight, we went to a member's house and had about 3 hours of learning to differentiate quality of light. Usually I'm just happy to see anything but grey.
Bookmark this outstanding article by a really talented guy, and none more generous to spend his free time with us hacks, by Guy Grube.
http://guygrube.com/Pages/pub_articles/wall_of_light.html
Might have to read it 2 or 6 times. Use your hand, it works.