You’ve committed to 50,000 words. Now how are you going to fill those pages? A yikes moment, for sure, but there’s no reason to panic.
Once you’ve fleshed out your outline, it’s time to start gathering material — a lot of material. Start looking for sources that can enhance the premise of your book. Think about the profile of the people you’d like to feature in your book. Where are they from? What kind of experience would you like them to describe? Then announce your search by posting on HARO (Help a Reporter Out), PR Newswire, Facebook, Twitter, and so on.
Also, consider existing media coverage. It’s fine to modestly cite examples — and by that I mean no more than a sentence or two, in most cases — that have been covered before, so long as you provide the source for your material.
Do add your own opinion, explaining why you included this particular material. Otherwise, you’re putting together a very extensive list, not writing a book. Provide your take on why things worked out the way they did and any caveats or lessons you can share with the reader.
In other words, make it your own.