This is a common experience. It probably would have helped if I’d been older than twelve, but, even so, your first experience of running a game will often abound with problems: errors in the rules, the tone, and in guiding the players to the right adventure. I’ve still have no idea how to run Trail of Cthulhu, for instance, and I could be considered fairly experienced in running RPGs.
I ran a session of D&D on Saturday night. It was horrid.
Even with much, much, much experience, things still go wrong. The adventure is too complicated. The players are contrary. You’re not on your game. It happens. The mistakes I made with the adventure were not those of my 12-year-old self, but they were still things that caused the adventure to go wrong. It should have been more enjoyable than it was. Now, I must learn from what happened, and not make those mistakes again. Which means, of course, I will find entirely new ways of making mistakes.
Dungeon Mastering is limited only by your imagination. There are so many ways to do it. There are so many mistakes you can make. You get better by actually running games.
The current discussion on the styles of playing Dungeons & Dragons talk about three major pillars of play: Exploration, Role-playing and Combat. For me, combat is simple – you roll dice and defeat monsters. Exploration is when I get to invent silly things for the players to find. And Role-playing is when I get to do silly voices to interact with the players. I’m best at exploration: coming up with silly (but interesting and engaging) tricks for the players to interact with. I’m fine with combat – a great understanding of the rules, but I do less well with encouraging improvisation from the players. And I’m merely okay with role-playing.
So, when I design my own adventures to run, I play to my strengths.
From my perspective, it’s easiest to learn the combat rules. So, if I were learning to run D&D again, I’d start with a simple dungeon with a few monsters in it. No more than three or four rooms. Then, for my first session, I’d have the players enter the dungeon, fight the monsters, and take the treasure. Very simple, and it gets you a taste for running the game that isn’t overwhelming.
However, perhaps you find role-playing easier. Or you have a bunch of strange tricks you want to introduce your players to. Do it! Use them! Not every adventure has to be about orcs!
About the only advice I can give that applies to everyone (well, almost everyone) is this: Start small. You can build things up later.
It’s fine if you forget things. Just pay attention to what your players are enjoying: those are the things you got right!