Many of us, have read GM-sections in RPG, RPG blogs, forum discussions, and sometimes books about the storytelling art.
All of these contains tons of interesting tips/techniques (and some will contradict each other, you don’t GM a gritty mega-dungeon and high-school drama game the same way), so I am curious which ones are your favourite and how do you use them in your game
When I first started DMing as a kid, my dad told me the best thing I could do to prepare was just know the whole world. He then told me about an adventure he was running where the players, for literally no reason, started digging in the middle of a tunnel. There was a whole dungeon set up for them ready to explore, and they went 50’ into the tunnel and started digging their own tunnel.
I think better advice in that situation is to find players who want to play the game you’re running. It might be fun to make a tunnel-exploration campaign, but I’m running that dungeon over there. We’ll do the tunnel thing another time.
Also, to rephrase your dad’s advice, know enough of the world to be able to add shit where you need to. I don’t even know if the world is round, but I don’t need to. If the players are in a church, I’ll make sure to know the popular religions in case I need to roleplay as a priest.
The players will find a way to make you need to.
You decide that if an when the players make it a priority with their choices.
No, the world is enormous and you only need to worry about a small part of it. There is literally nothing over there, and no reason you’d want to go there. The game is over here. Leaving this area is the same as leaving the game, which you are free to do.