Seth Godin has some great advice for new authors:
Build an asset. Large numbers of influential people who read your blog or read your emails or watch your TV show or love your restaurant or or or…
Then, put your idea into a format where it will spread fast. That could be an ebook (a free one) or a pamphlet (a cheap one–the Joy of Jello sold millions and millions of copies at a dollar or less).
Then, if your idea catches on, you can sell the souvenir edition. The book. The thing people keep on their shelf or lend out or get from the library. Books are wonderful (I own too many!) but they’re not necessarily the best vessel for spreading your idea.
And the punchline, of course, is that if you do all these things, you won’t need a publisher. And that’s exactly when a publisher will want you! That’s the sort of author publishers do the best with.