Looking At A Work Of Art, is a wonderful list of questions to ask when discussing a work of art during picture study.
Mozart & Mudpies blog has a wonderful post about how she does Picture Study with her daughter. I think I'm going to implement her "Let's play a game." idea because I have a child who loves games.
Mater Amabilis Picture Study
Ambleside Online Picture Study
Looking at Paintings: Developing a Story From a Painting