It's interesting to see the different responses people have had to Hill Cantons challenge to name their best practices as a GM.
Some, like keep the game moving, I completely agree with. If things are slowing down too much while you look up rules you might need to spend a bit more time learning the system or choose a game that doesn't require you to remember quite as much.
Other suggestions like "always say 'yes' to the players" or "while the players are trying to guess what's going on, change things to be whichever of their guesses you think is most interesting" I completely disagree with. This is antithetical to what I want from an adventure roleplaying game and I would choose another type of RPG instead -- tactical, boardgame, storytelling style etc.
Here are the 3 things I think make a good GM and which I try and keep in mind when running a game.
As a Game Master you may also have written the scenario, but that's not your job as the game master during the session. Once the game starts you should try and be as impartial as possible acting more as a referee than "omnipotent benevolent dictatorial storyteller". If you are leaving something to chance, then roll the dice in the open so everyone can see it was left to chance. If you aren't leaving it to chance - just say so. Don't change the statistics for the monsters, locations of the rooms, or add / remove elements to "keep things interesting". If you are using a map and key, let the players know that. If you aren't using a pre-generated scenario… let them know that too. It might change what the players spend their time on, and it's only fair they aren't wasting their time.
The second best practice is making sure the choices the players are presented with make a difference. Don't ask them if they order beer or ale in the Inn if it doesn't make any difference to anything in the game. Don't ask them if they go to the West or East if you intend them to encounter the Evil Wizard regardless of which door they choose. Rather than railroad your players or present them with false choices just narrate whatever you need to setup the scenario and then give them real freedom around the choices they make from that point on.
Of course fairness and meaningful choices might not be important if you're running a game about improvisational acting or storytelling, or a game where the adventure is just the fluff between the "fun" of detailed tactical miniatures combat. However if the game is about the adventure itself then you should also be making sure there is a balance between the different things that make up an adventure. Tactics and deep in-character acting should only be a small part of that while exploration, mystery and solving a variety of problems they encounter along the way becomes the focus.
GM Merit Badges
What would be great is if GMs had merit badge style indicators of not only what they thought they did well, but also their general philosophy around how to run a game. Knowing two GMs are both running games of D&D is less important (for me anyway) than knowing that one believes in letting the dice fall where they may, while the other believes the dice shouldn't get in the way of telling fun stories with interesting and long-term characters. Even if you'd be happy to play in both games it would be good to know this stuff ahead of time.
That might be something to think about more in subsequent posts...