These are pretty basic, but things like not knowing the rules or your audience/players can ruin any gaming session, regardless of system.
Dungeons And Dragons is awesome and fun and crazy, but if you’re not careful, it can also be boring, awkward, and shitty. Often times the outcome is dependent on the Dungeon Master (DM). I’ve been DMing for longer than I haven’t been DMing, and a lot of people tell me I’m a great at it. I don’t believe them, but despite this, I contend that my successes are based on a few key areas I like to drill down on (as well as shortcomings I try to avoid in my travels through various roleplaying circumstances). Here’s a few areas where I think Dungeon Masters tend to fuck up, and ways they can fuck up in their attempts not to fuck up.
#5. Not Knowing The Rules
Role-playing games are for nerds*, and nerds are known for their mastery over minutia. The Dungeon Master is the Alpha Nerd* — the beginning and end of the game, the universe and the god and the world and the history and the physics engine and the set dressing and the props and all the different ways those things interact and work together. And that means knowing a ton of rules. DnD is a lot like sex: when it’s good, it’s good … when it’s bad you just want to leave, and when you’re constantly stopping to look things up it kills the mood.
*not really but just go with me for a fucking second