Pre-production, or prep, is in many ways the most important part of the shoot. Prep is about imagining the worst-case scenario and doing everything possible to avoid it and so requires imagination, communication and execution. Most of this imagining stays private, but those elements that involve taking action will be shared. This chapter discusses the pre-production work involved in an example scenario of a six-week shoot with a four-week prep for the First assistant director. Screen Actors Guild (SAG) is in many ways the most important union for any production, as even on the lowest-budget projects, where the entire crew may be nonunion, the actors will almost always be SAG members. SAG divides filmmaking practices into a number of tiers, based on the budget level. The most important thing to remember when dealing with SAG is to be totally honest and transparent.