Koster, best known in MMO circles as one of the minds behind Star Wars Galaxies, Ultima Online, and Metaplace, offers plenty of advice on everything from dealing with people who tell you that you're awesome (these folks are "useless, no, dangerous") to digging for good feedback to the fact that all of your critics are right.
"I've never gotten a piece of feedback that was wrong," Koster explains. "You see, you can't deny a player their unique experience. Whatever they felt was true. For them. And something in your work triggered it." He goes on to say that "self-doubt is one of your most powerful tools for craftsmanship." Aside from having "the arrogance to assume anyone will care in the first place," self-doubt is healthy and necessary because creatives are never done learning.