What behaviors might attract the ghost to you?

The biggest thing that attracts a ghost to you in line of sight and sound. Having low sanity will make hunts more frequent, but as far as I know, it doesn't affect who gets targeted during a hunt.

However, a ghost having line of sight to your character means that you're likely to be targeted. Ghosts seem to have a perception based on a cone coming from their character, meaning they may not spot you if you're behind them or far enough to their peripheral. If you're in front of them, directly in their sight then they'll likely target you.

Next is sound. Ghosts investigate the locations players spoke at. During a hunt once line of sight is broken (or never established) it is important to keep quiet as to not attract a ghost to your location. Ghosts can hear sounds in their proximity meaning they may hunt you down even in an enclosed room if the players don't stop talking. It is crucial to note that ghosts can hear all voices, even if push-to-talk isn't pressed. If you're muttering to yourself even without speaking to other players the ghost can still locate you.

Now, what happens if the ghost spots two players at the same time? It's still unclear but it seems to be random, or close to random on who gets targeted. Sanity does not seem to correlate with who is targeted, there are a few videos of players standing close to the ghost while it runs past them to target other players, so it may be determined by who is unlucky enough to be seen first by the ghost. This is still unconfirmed and the ghost is known to switch targets during a hunt, especially if other players come closer to the ghost.

Lastly, while it doesn't attract the ghost to you, hiding in the ghost's room is dangerous during a hunt because the ghost spawns in or adjacent to the room and roams the immediate area. This when attempting to hide you may still be spotted as the ghost patrols more thoroughly in this zone than elsewhere.