3: Write to your audience
Know your players. Ask what they like and what they want to see in the game. Vital, ASK. Don’t assume, poll the players, inquire and check things out. Their role in the game is as important as yours.
On that note seek adventures of mutual enjoyment. If you are a sea adventure bunny (like me) and your players are not (like mine), then don’t write sea adventures. Write something you both like. You are part of your own audience. If you don’t like what you are doing it will show and enjoyment will be lessened.
Explore the limits, but be careful. Pushing the limits can be a good thing if you do not push then too far… Push people’s limits too far and they get uncomfortable. uncomfortable people are not having fun. People that are not having fun stop coming. Don’t even go there if you do not know your players very well indeed. It’s a game, not a psychological test.
This one feels obvious, and I see it broken all the time. The GM that gets too far into their own thing, and forgets the “collaborative” part of the game. That is key. RPGs are collaborative. Without the players you the GM are nothing but a hack novelist that can’t finish a story. Everyone should be having fun.
I do find it useful to query the planers as to the overall direction of the game. Obviously you cannot go over your exact plans. I don’t just do it before starting a campaign, but during. Does it need a new direction, short stuff or an epic dungeon?
Recently one of my players had a health incident. She has been pulled away while she recovers. The rest of the group asked me to put the current campaign in abeyance until her return. They rolled up new characters. We are doing something different for a while. The other will keep. (Speaking of which I need to order the minis.) Life throws rotten fruit at you. Deal as you must.
I have been in games were the GM did their own thing without listening to feedback. It became a chore and I quit. When I leave every session fuming? Yea, no, that is not fun. You do not want to be that GM.
So keep your ears open, and ask.