How many players will you need? Technically, you can run a game one-on-one, with just you and one player. However, a two-player game allows them to interact and roleplay; adding more players increases the interaction but also the work required on your part. I like to have either three or four players, which is a good balance between fun and ease.
So now you hopefully have a few possible players and have pitched the story to them. Discuss things with them and find out what sort of characters they would like to play.
Now you face a choice: Will you create characters for your players or let them do it themselves? There are several factors:
If you allow the players to write their own characters, you’ll probably want to get together long before or set aside an hour or two before the session. Help those players who are unfamiliar with the rules and walk them through creating a character. Have everyone brainstorm about whether their characters know each other and what they have in common. Try to get them to care about their characters and invest in them.
If you decide to create the PCs yourself, you should still let the players be involved so that their characters feel personal.
Try not to make any one character crucial to the plot, in case the player can’t show up on game night.