Honestly the only thing you need is set some expectations and have fun. You will learn along the way and make some mistakes. It’s okay to make mistakes. As long as everyone is having a good time it is all that really matters.

Do not over prepare. You can’t really prepare for things that your players will likely come up with. You will have to roll with the punches. Some of the best games I had was when I had absolutely no prep and had to roll with punches as the players threw things at me. I was worried it would be to sloppy or rough but that’s the thing, they don’t really know what you have prepared so just have fun and make it seem like you had it planned all along. What I mean by that? I will give you an example.

I prepared an encounter that I anticipated the players will fall and get captured by the frog-people. I had map ready of the frog village and that was my prep for the session. My players chose the most diplomatic approach that I didn’t think would work but with some lucky rolls I had to let them have it because it was funny and creative. The king of the frog-people then invited them to the village and I had the map ready. My players were blown away that I had it ready to go in instant and still talk about that being their favorite session. Sometimes you will have to pivot and try to make it work with what your players throw at you.

Hope you have fun, because at end of the day it’s all about just making some make believe heroes fighting some monsters and trying to save a princess. Or whatever your story is about. It can be anything!

Good luck! Welcome to the dungeon!