The blog Abstract XP calls Kobold Guide to Game Design from Open Design recommended reading.
And it is the writing style as much as the content that makes this publication work. It reads like a learned favourite uncle (Uncle Wolfgang in this case) has sat you down and spun you some home truths about writing fantasy adventures.
… I do recommend this publication. I recommend it to anyone who wants to be a better GM. And anyone who doesn’t want to be a better GM—your players don’t deserve you.
We’ve got a little something for everybody. Pick up your own copy of Kobold Guide to Game Design.