Nobody ever knows what they're doing; we're all just pretending.
That's sort of true of life overall, but we're focusing more on role-playing games today.
There are 100,000 things going through a Dungeon Master's head during the course of a game. When you run a game, you have to try to keep track of what everyone at the table wants to do (depending on your group, that's no easy feat); you have to track where the characters are in the world, especially if you have no reference at the table, purely theater-of-the-mind; if you do use miniatures, you have to keep track of maps and minis.
Then there's the story - you have to track what has already happened, everything happening in the moment, and any story beats you are setting up. If you're running a combat, you have to track turn order, the abilities of each antagonist, and any conditions going on at any given time. And then, when your players inevitably throw you for a loop, you have to adapt everything you are doing to adjust to their actions.
It's a lot to keep track of, is what I'm getting at. But here's the great thing: it's what every game master goes through in every single session.
There isn't a magic hack to running RPGs, and that's both good and bad news. The bad news is that there is no magic bullet to running a good game or a good campaign. When I first started our Tyranny of Dragons campaign, I hoped that using a pre-written adventure would allow me to get my feet under me as my group learned 5th edition. However, while it's a decent adventure, Hoard of the Dragon Queen is not a perfect book. So I spent a few weeks scouring the internet, looking for articles about what worked and what didn't, which chapters fell flat and needed some punch-up, and which moments in the adventure tended to excite players. Then I had to actually integrate my core cast of characters into the story, and so I began looking for exciting ways to integrate my PC's backstories and motivations into the adventure.
Then our group began to swell in size, and that meant the encounters were too easy, so I had to start buffing them up... additionally, due to some creative character decisions, the narrative began to take a different shape from the plot suggested in the book, which meant I had to do a bit more prep... all this to say, all of the support a pre-written adventure provided kind of fell apart, and I basically wound up running something homebrew just to keep up with the needs of my party.
When I look online and people ask questions about running games, the bad news is that there isn't a secret hack to it; you just have to start running games and learning as you go.
And that, I'm happy to say, is also the best thing about being a Game Master. Because no matter who you are, that is the only way to get good at running games.
Some of my favorite actual-play GMs - James D'Amato (of the One Shot and Campaign Podcasts), Kat Kuhl (also of the Campaign Podcast), Matthew Mercer (of Critical Role), and Brennan Lee Mulligan (of Dimension 20) - all make it look easy. There are some episodes of One Shot that feel like artfully designed narratives, Kat Kuhl ended Campaign's Mandalore arc by tying weeks of ridiculous meandering into an incredibly satisfying climax, and as someone pointed out, the moments where Matt Mercer has to consult his notes are actually incredibly reassuring, as they validate that he doesn't have an entire universe printed on the inside of his skull that he can recite from memory.
And I could teach an entire college class focused entirely on Brennan Lee Mulligan's four episodes of Exandria Unlimited: Calamity.
Yet every one of them had to learn by doing. Sure, you can read all about DM advice online (and I hope you do, since I'm literally writing about that every week and making a whole bunch of videos about it), you can watch actual-play videos or listen to podcasts, and you can prepare your campaign as thoroughly as you like, but at the end of the day, the only way to get better is to practice. The only way to run great games is to start running games until they get great.
Of course, I never want to let on to my players that I don't know what I'm doing. Sure, I can confide in them before or after the game, let them know I'm not sure about the rules, or I'm still getting used to encounter design - that's totally fine. But once I sit down to run a game, I try to turn that stuff off. I don't have to pretend I know all the rules, because you can always rely on the group to help with things like that. When it comes to the story itself, you have to trust that you can handle whatever comes next, even if you are entirely out of your element.
In the third or fourth session of my second campaign ever, my players surprised me by arranging a meeting with the enigmatic villain pulling the strings on the entire story. I wanted to reward them, but I also didn't want to reveal the villain yet. So I paused to go to the bathroom, where I wracked my brain to come up with some intermediary character I could use - someone like the Mouth of Sauron, who maybe wasn't a major antagonist, but could speak on their behalf.
I started running through a list of Biblical names, and decided "Isaac" was good - it was the perfect blend of modern and ancient that it felt timeless, and isn't as strongly associated with any particular characters as other names are (like "Peter," "Gabriel," or "Peter Gabriel").
But what race to make Isaac? Well, tieflings are pretty cool, and we didn't have one in the party, so they were a good combination of exotic and dangerous.
Okay, so I had a name and a race, but I didn't have a character - what was Isaac like? Imposing, or mild-mannered? Creepy, or polite? Then a scene from the final season of Lost popped into my head (very mild spoilers for season 6), where Sayid sits down for a meeting with a gangster threatening his family:
(There was a similar scene when Malcolm McDowell's character was introduced on Heroes, but the less said about that show, the better.)
The idea of a scary criminal sitting down and eating eggs in front of you, while discussing business in a perfectly reasonable manner, was really appealing for my evil emissary. So, I basically lifted this scene wholesale - I had Isaac meet the group at the tavern where they were first hired, casually eating eggs when they arrived. I liked that it implied that Isaac was not a fighter, because otherwise he likely wouldn't let his guard down, but he would still be confident, possibly to the point of arrogance. Isaac wouldn't be nearly as physically imposing as Kevin Durand, but instead he'd double-down on being polite, offering to buy them all breakfast.
The group started asking questions about the villain, and Isaac started answering them, which meant I had to start coming up with answers quickly. When they asked about the fate of their contact, a local merchant who had first hired them. Isaac's response was vague, but unambiguous - the merchant may be dead, but even if he's not, he's not having a good day. Then Isaac started talking about his boss, and how they worshiped an evil avatar of death.
Our wizard delivered a cool line: "If you guys worship death so much, why don't you just die and get it over with?"
Isaac's response: "I already have. Everyone in our group has crossed over and tasted the other side. We wish to bring that peace to the rest of you. We wish to bring death to this world."
My immediate thought, as the person who literally just said that: "Uh... okay, I guess that's a thing."
My roommate later confirmed that the scene was as creepy as I hoped it was, and that made me happy. I still look back and think I could have handled it better, but considering how quickly it came together, I'm still pretty proud of that moment. Necessity, after all, is the mother of invention, and thanks to the old trick of "making things up and pretending you were planning them all along," I was able to give my evil group of necromancers a face, a voice, and a motivation. And that made it much easier for my players to interact with them, and engage with the story.
For those who are interested in getting into GMing, but think it seems too daunting, I have this to say: That feeling never really goes away. But over time and with practice, you can learn how to do it anyway, and do it well.