I've tried Ouija boards before, or glasses, and stuff, and it can be spooky, or feel as if it is, but then it's not that different from watching a scary film with some friends, you prepare to be frightened. Someone darkens the room, turns the lights out, puts candles on. There's been a few drinks, some laughing and joking, then you get serious.
The important thing is, whatever comes out is no-one's fault, and because of this, inhibitions can be loosened, taboos can be spelt out. It's a group thing, and interesting enough just as that.
Actors do similar kind of things, and writers have all sorts of techniques to put themselves into areas they are uncomfortable with.
It's not much different from the word association thread.
The big difference is the proximity of other people, and their desires to influence the group, and a willingness to interpret 'messages' from the board as if they have a purpose. They don't have a purpose, they're improvisations, and their only source is the group. That's interesting enough, for me at least.
But if you want, or must have, more 'meaning' to them than that, perhaps don't do them is the best advice.
Otherwise, make up a name, an age, a place, and a character is there. Enjoy.