I think having a strong core and mood to the game helps a lot. The more specific and focused the game is, the easier it is to give advice about how to run it. PbtA is usually pretty good for this, seeing as most examples are trying to simulate a certain genre. For myself, based on my own experiences GMing, my primary focus is to keep things moving. Having a game stall out or get stuck in combat or whatever for an hour just isn't fun for me. It's just exhausting. Maintaining momentum and energy and keeping up that sense of progression is my number one priority. So everything is kind of built around that, I have advice for dealing with a string of partial successes, skipping ahead if a scene is dragging, introducing wrinkles or changing things up if a scene is flagging. I also include a lot of play examples, because I think they really help illustrate how mechanics can work when you're actually playing. And of course I include a bunch of caveats--this is how I play this game, but don't take it to be prescriptive. If something isn't working, drop it. If you want the game to be different, change it. If everyone's having fun and excited about what might happen next, it's all good.