Theo Epstein is interviewed at Baseball Prospectus (hat tip to Al's Ramblings).
I liked this exchange:

BP: What do you do to make yourself better at this job?

Epstein: I think listening is important. And being actively aware, every day, that you want to get better is the most important thing. Then you can't help but learn from the great people around you. I benefit from having people like Bill James, Bill Lajoie, Craig Shipley, Josh Byrnes, and Mike Port all around me. And they each have an area of expertise. It's as if I'm at Baseball College--you go to college and you take your classes and get to learn from experts in certain fields. You know, if I want to go watch a game with Bill Lajoie, maybe I can pick something up about a pitcher's delivery, and then later in the day maybe I'll have an e-mail exchange with Bill James and learn something about some metric. As long as I'm open-minded I can't help but get better every day.

And also making mistakes. It's definitely true that you learn your hardest lessons from your own mistakes.