Advice from Francis Ford Coppola:
I'm going to tell you the story of how I prepared the actors of "The Godfather." Of course, we were all nervous about Marlon Brando. As theatre students in the '50s, we looked at him as the greatest. And there was going to be the first time when all the actors were going to meet. Of course, Al Pacino, Jimmy Caan, Bobby Duvall, Johnny Cazale -- everyone just admired Marlon. He was the Godfather. I knew that, and I said, "I can use this." Napoleon once said, "Use the weapons at hand," and this is what a film director has to do everyday. So what I did is I arranged for the first meeting as an improvisation.
I said, "I want you to come and be hungry." And they came to a restaurant that I had arranged, the back room of the restaurant, just a table that looked like a home. Marlon, I had sit at the head of the table, and to his right I put Al Pacino, and to his left I put Jimmy Caan. I put Bobby Duvall, and I put Johnny Cazale, and I had my sister Talia, who played Connie, serve the food.
They had a dinner improvisation together, and after awhile everyone is relating to Marlon as the father, and Jimmy Caan is trying to impress him with jokes, and Al Pacino is trying to impress him by being intense and quiet, and my sister was so frightened -- she was serving the food. And after that dinner they were the characters. So one tip I give you is, with improvisations, they really stick if there's something sensual connected with them, like food or eating or making something with their hands.