Read June's Magic magazine for Paul Harris's ideas on creativity.
Personally, I think it just takes inspiration and time. If you're really creative, you can do what Eric Mead wrote about in "Tangled Web" and simply ask yourself: "What is the desired effect?". In the context of your personality and performance, of course.
Creativity in magic isn't for everyone. If you can perform other people's creations in a unique and dramatic way (DB's pulse stop/glass walk), that's all that matters. Performing creations that are fairly solid while taking notes about reaction/timing/patter etc. should help you get a better idea of what needs to get done.
One last Paul Harris advice (it was given to Eric Mead- one of the best guys around) is to find something that you think has to be done- that no one else is doing, and do it.
I would ditch the formula, by the way. I doubt it will help.
Our favourite Mr. Kras will undoubtedly point you towards Jay Sankey's book "More than Secrets" and his (Sankey's) DVD on creating original material. Maybe Darwin Ortiz's book "Designing Miracles" as well- if he read it. I just wanted to steal the pleasure of doing so...

Seriously though, Ortiz's book is excellent.