- Founders at Work: Stories of Startups' Early Days by Jessica Livingston. [2]
[1] http://www.amazon.com/Four-Steps-Epiphany-Steven-Blank/dp/09...
[2] http://www.amazon.com/Founders-Work-Stories-Startups-Problem...
I would also recommend the ultimate sales machine. Even though I've only read 20 pages since I started reading it one month ago (yes, I run a startup), it's really interesting and helpful.
In earlier times, here are the books I found to be particularly useful: http://news.ycombinator.com/item?id=1021570
Others have endorsed E-Myth and I'll note that what's most valuable in Walking the High-Tech High Wire is in part their Customer Discovery story....
The next question you might ask is: how much time should I spend between reading/learning vs. actually doing stuff which this question might help: http://www.quora.com/How-much-time-should-entrepreneurs-spen...
Ignore what the critics say about this book because I think this book's strengths is in their case studies on the company cultures and qualities that made them successful decades ago. This is more about how to treat people and direct a company, while providing examples of how these companies had dedicated passionate micro teams who were their "lean startup" champions that drove their innovation and success.