Fortune Teller - Townsfolk

Each night, choose 2 players: you learn if either is a Demon. There is a good player that registers as a Demon to you.

You have a very powerful role and ideally want to live a long time. This means hiding yourself from all but those you trust (usually players killed at night). Surviving as a Fortune Teller can be very difficult - you can try bluffing as roles that want to die at night, like Sage or Ravenkeeper, or roles that are low priority for execution and night kills, like Butler.
Your Red Herring is probably a powerful good role, which makes discovering which of your “yes” pings is correct can be difficult. Both will likely want to live, and only one is the Demon.
Keep in mind that you can check someone else against yourself. This is useful to test someone by themselves and avoid tainted information from other sources.