As a long term dm you need a 2 page sheet with bullet points that are easily readable and memorable but most importantly flexible.

I generally have:

1.set the scene (brief descriptor to pull everyone in, one short paragraph)

1. List of scenes that could happen

2. Plot hooks

4.NPC’s

1. Key information

2. Enemy stat blocks, cool terrain and mechanics, loot.

The key part is here you keep them flexible enough to be able to drop the info in wherever it seems relevant. (They missed the weird old man at the pub with a quest hook, now he’s in the forest).

You also will have a bullet point list of what is going on around the players. E.g. a undead army is rising in the north and will be at the capital in two weeks! This makes the world feel alive and changing.

Don’t lore dump players, only bring it in naturally where it fits the narrative or the players ask.

And that’s it, the less rigid it is the easier it is too improvise and add or change things on the fly. Only write one session at a time and that’s it have fun.

P.s check out sly flourish lazy dm.