Tip #282: Finding your core audience

“Let’s just say I will give you $50,000 if, in the next hour, you can find 5 people who would love your book.”

...Now, with $50,000 on the line for a mere hour’s worth of work, your mind begins racing. You get super specific. You think of the core themes or topics in your book; you think of competitive books who have an already established audience. Then you consider the exact physical places you can go to reach these readers; the ways these people are already organized – already self-selected and filtered based on previous behavior and interests; you think about who has access to these people; you consider where these people are online and off; you focus on actual names of people you can call at this very moment.

http://writerunboxed.com/2012/08/24/do-you-know-who-your-audience-is-no-really-do-you/
Why is finding your core audience important? These are the people who will tell others "you have to read this book!"