This video provides tips for how to effectively tell your story. Since this is a documentary and not a fictional movie/story not all of the elements apply but do pay attention to the elements like the soundtrack, narration, and pacing. Some of the hints this video provides:
-for your soundtrack don't pick music with words that will compete with your audio narration. This will distract the viewer.
-pay attention to pacing. By focusing the timing of your edits you can increase the dramatic tension and reinforce what your interviewee is saying. For example you can pan or do a close up of a still photograph.
The following are student made documentaries that won the National History Day Documentary contest. Notice the intermixing of music, still photographs, and interviews to create a story rather than a static interview.
From the University of California, Santa Barbara this document outlines how to create a storyboard for a documentary. Pay particular attention to the final three pages. They provide a sample script (along with accompanying images) as well as a checklist for your project.
Want to get fancy and do your storyboard online? This generator will allow you to create a storyboard with online photos.