Before you start shooting, sketch a "map" of your video using storyboarding. Each board represents a main point, image, or scene in your video. Organize the boards along with your script to plan your video -- like writing an outline before writing a paper.
You can use software like MS PowerPoint or StoryBoard That (see below) or you can sketch out your ideas on a whiteboard or a sheet of paper.
Storyboard That is available as a 14-day free trial. You can create two storyboards per week.