One of the many quotes featured at the signature of a friend of mine is “Learn from mistakes of others; you won't live long enough to make them all yourself”. It is important to read success and failure stories of what people did, what mistakes they performed and what are their conclusions.
I believe we can learn more from the failures of ourselves and others, than we can learn from successes. That's because in a success, almost every aspect was done right, while in a failure one can look back and say where things went wrong.
You can find many such stories on the Internet, and sometimes you'll hear about them in news sites, blogs, and various forums.