I rarely make this kind of composite stuff because I don't have nerves :) But this time I really realized how much easier it is to first make the background, whatch the source of light carefully and after that go and shoot photos from the subject. Matching different stock photos together is so much more simple when you have made the steady ground.
Do you make first the background before you shoot your subject?
I usually shoot first, then the ideas flow from there, but I'm starting to move more towards choosing the background first to inform the lighting.