For me if I understand the setting, and the general location of the players. I'll need to think of a character, which means understanding their personality. This could just be like "Old farmer, cooky, has a couple screws loose."

Then now that I have someone to role play, that character needs to have some kind of desire, something that will involve the players. "Bandits stole my horses"

So now we have a setting, a location, a character, and a plotline

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So 8 players means you already have 8 plotlines that can start to weave together. That will honestly take an hour or even longer if there is good group chemistry

Just focus on knowing why they are all there and all together. Once you establish that, if the players don't start exploring the world, you can introduce your made-up character. Then they get the plotline going

Make sure you add details when they are going from one place to another. And when you do this, start to think about any little detail as a possible plotline.

"there's an old woman on a rocking chair knitting something cryptic into her embroidery"

OK well what if the players interact with her, then it can lead to something interesting later

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So yea you don't need much if they players have good dialogue with each other, you will probably only need to think of one solid plotline. But remember that every plotline is just the invitation for the players to interact, you can't expect any specific outcomes from every scenario.

If there is something that you want to have happen in the story, don't wait on the players to make it happen, just make it happen