I read a good article today on Backstage.com entitled "What Does Real ‘Prep’ Really Look Like?"
The author stays out of the murky waters of stupid acting teacher catch phrases! YAY! However, he never really answers the question that might be on your mind as an actor who has just been hired to act in your first Television or Film role. His approach assumes that "prep" is more of a Sanford Meisner term for you and not an actual process. For those unfamiliar with the "Meisner prep" it is a tool which is used to work into the emotion of a scene. This tool is an evolution upon Stanislavski's use of Sense Memory recall using less memory and more imaginary circumstances... that's a whole other blog for someone else to write.