I mentioned in an earlier post that context is important. That is to say, what other films exist on the topic, what other films exemplify the style/form desired, what additional information can be gathered up to help make the film? These are key elements of pre=production. They are also, at a preliminary level, important questions to explore to determine if a given film idea is feasible: perhaps others have already done something very similar, or serious problems exist regarding rights, permissions or archival material, or perhaps the way the issue’s been framed just isn’t clear enough, something that additional research may make clear.
If a film is personal or autobiographical the lack of duplicate material is assured but models for how to do it can be quite vital. Tarnation, for example, adopted a wildly flamboyant style and incorporated home move footage from early childhood up; it contrasts with the much more sedate but somewhat tongue in cheek style of Sherman’s March, the witty but loving style of Nobody’s Business, and the utterly fabricated but very convincing self-portrait offered by David Holzman’s Diary. Tackling this type of film, looking at one’s life as subject matter for a film, invites reflection on the autiobiography as a literary form going back to Montaigne and Rousseau if not St. Augustine. It has gained great popularlity in the last few decades and trails into the world of reality tv on the one hand (exposes and confessions) and of essayistic meditations on the other.
These are some preliminary points to consider. Every project is unique and the specific steps depend heavily on the particular ideas and goals that characterize your own project.