The movie star has opened up to the Los Angeles Times during a roundtable chat with fellow filmmakers Martin Scorsese, Alexander Payne, Michel Hazanavicius and Stephen Daldry, and admits there's a trick he uses at the start of filming that lets his cast and crew know he means business.
Clooney, who is among those being considered for a Best Director Oscar nomination for his work on The Ides of March, admits he picked up the idea from legendary moviemaker Sidney Lumet.
He says, "You set up the first day, the first shot, something you will never use in the film. And the crew's there and you go, 'Ready, action'. They do the first take. You go, 'Cut, print, moving on'. And everybody in the crew just sits up."
Clooney admits the trick helps him get the best out of his actors.
He adds, "For me as an actor, if someone does that to me, if you think you're going to do 30 takes, you sort of tank it in the first five or six because you figure they're not going to print it.
"You've got to be on, and it's funny how you feel everybody kind of sit up in their seat."