I try to take inspiration from lots of sources, particularly ones that aren't particularly Star Wars related (as I think it helps generate wider ideas). For example I enjoy looking on sites like Deviant Art as there are hundreds of brilliant drawings and paintings and suchlike. Also more relevant to this topic I have considered other films and stories with big twists. I would say a couple of brilliant examples are the Prestige and The Eternal Sunshine of the Spotless Mind, where once you have seen the film for the first time and you become aware of the twist, when you watch it again you notice all the little clues and things that were included to make it consistent with the twist, but during the first viewing you thought nothing of it.

That is exactly how I think the Anakin Vader reveal should work.