It looks like a good start Steve. The only thing I noticed is that the blue that you painted on the backdrop for sky is a lot darker than the color of the sky in the commercial backdrops. I think sometimes getting the right color for the sky is one of the most difficult things to do. We usually tend to want to make it darker than it really is. I think also that if you can't match the sky in a commercial backdrop or you use different commercial backdrops and the sky doesn't match from one to the next, the best thing to do is carefully cut the sky out of the back drop before mounting it, and then establish your sky color and paint your backdrop with the sky color and then glue the building pictures from your commercial backdrop to the blue sky you painted.
