The Economist has a MBA series, including what and where to study MBAs, how to write your MBA application, and how to write the perfect MBA essay. I think the latter two links are worth saving, even if you’re just considering an MBA.
Of course, if you prefer to take the self-study route, you could try this list of the 99 best business books ever.
Lastly, you might forget the whole thing and build your startup company on your own.