When someone claims to be psychic or talk to the dead there's a couple of ways he could do it. The simplest way is to have a schil or confederate. One time a man claimed to give an actress his "vibe". She was an actress and she was obviously faking it. Another technique is called working the audience. They start general, then move in on a target. And they always seem to say they're looking for someone whose grandmother's name begins with an M. Well, we have two grandmothers and...
"Here's something to think about: How come you never see a headline like 'Psychic Wins Lottery'?" —Jay Leno "If it's the Psychic Network why do they need a phone number?" —Robin Williams. "It is difficult to make predictions, especially about the future." —Yogi Berra.
Talking to the dead doesn't work like that. It is simply quieting your mind enough to distinguish internal monologue from a telepathic thought. The living and the dead are capable of telepathy. Generally speaking you will be the reciever and you do not get to steer the conversation. You also have to make a connection or find one. We are all connected in some way-- close relatives are relatively easy. once you find the link, you can recieve the thoughts of the deceased person. You probably won't be able to speak about worldly things. In fact the less you focus on the material world and its concerns the more you can recieve the message. The thoughts of others, both living and dead flow in and out of your mind daily. We routinly mis-identify this as our own thoughts or filter things out. Monastic practices such as fasting celebacy, meditation and martial arts (or tai-chi) tune us all in to the inner world. Entheogens can also help train a sensitive person.