Slayer - Townsfolk

Once per game, during the day, publicly choose a player: if they are the Demon, they die.

You are a powerful role, but without the help and information gathering of your good team, you are very unlikely to be successful. Make alliances, seek out information and use your one shot wisely.
Your ability has two very useful purposes - confirming someone as not the Demon, or killing the Demon. It can be tempting to save it for the latter, but in a pinch the former is still extrmely good information.
If you suspect you will die soon, whether by execution or Demon kill, use your shot on someone the town has suspicions about. Either they are the Demon and they will die, or they are not and your team can start building other worlds.