Ask a lot of stupid questions. The more obvious the better. Unfortunately companies often forget to define their project and their goal clearly. I don't mean just Windows, DOS or Macintosh. I can't stress how important it is to be clear from the beginning what response you want to elicit from your users.
Multimedia is neither linear nor a blob.
Your job is to make sure users can easily hop from one island to another. Put each screen on your chart and show how your screens are linked to one another. Too many layers. Don't force users to wade through dozens of screens to access the information they want. They won't bother.