In the iTunes U app, there's a course called "Mobile Journalism: Become a Citizen Journalist." One of the sections in there is called "Virtual Storytelling". It's really interesting, it has lots of videos and articles to read and learn about to help you become a good visual storyteller.
From the articles and videos I've seen, there are many important key factors. Characters, Setting, Emotion, etc. Characters. You want to interview people who you want and will be good for the subject of the video. Setting is the same, you want to shoot at the right time and the right place. If your video is about a basketball game, you don't want to shoot the interview at a park. You want to shoot at a basketball court, or THE basketball court. Emotion. For every action you film, there should be enough reactions.
Visual Storytelling is amazing, but to create a good story, you need to know the key elements.