Organization key to a well crafted story
Tracking down sources did not present a critical problem. However, the process of capturing them on video with some unification from video to video was difficult. Creating a series of procedures to follow at the beginning and end of each video was an easy way to ensure that a similar presentation was acquired from each source.
Learning to plan out a story arch or figuring it out as the interviews are being collected also helps out greatly in postproduction. It is easier to edit and craft the story when the basic story line is already determined. Also remembering good quotes from some subjects make it easier to filter through all of the interview material and not having to keep going back listening to it.
Being organized and going in with a clear idea is critical advice, but also being flexible to changed in the story is necessary. Things wont go exactly according to plan, but having one to start off of is better then none at all.