In an interview with NDTV, the Talaash star said that while even he often wonders about his ability to choose a successful film, he simply approaches each script as if he is the audience.
"I've often thought about it," he admitted. "Luckily I've been successful several times and even I've been wondering, 'How do I choose these films? What am I doing right that I shouldn't forget?'
"Actually there is nothing. What I do is, I don't have any preconceived notions. I don't decide before that, now I want to do an action film or now a comedy film or a drama. I don't think about such things. Don't even tell me the story. Tell me the title. Sometimes there isn't even a title.
"To start with, I ask what's the title because I'm the audience - I want to know what the title is and then tell me the story. When I hear the story, when I'm listening to the story that time I'm the audience, I'm totally blank. I'm crying, laughing or I'm totally bored. I'm the audience at that time. If I like the story then I do the film.
"There are two or three things there. My decision is always instant, I never take time to decide. I take time to decide whether I want to work with you as a director."
The actor said that he was uncertain about starring in 3 Idiots, which went on to become the highest grossing Bollywood film of all time.
"When 3 Idiots was offered to me I said, 'Raju [Hirani], I can't play any of these three roles. A first year engineering student is the age of 18. I'm 42, 43, 44 or something like that. How I can I be 18? I'll be the laughing stock of the nation'.
"I liked the script and I wanted to act in it but I was afraid I wouldn't pull it off. Till then I was scared I would fail. The only reason I did it - and this is the only time I've done a film when I wasn't fully convinced - was because I thought there is something Raju has seen in me that I'm not able to see and I trust him so much as a director that I want to go with his instinct, maybe I'm wrong."
Khan's latest release Talaash has earned over 47 crore in its opening weekend receiving widespread public and critical acclaim.
A story of loss, the film has been particularly popular with women. "Yes, by and large women have loved the film." said Khan "Men are hard-hearted."
Watch the trailer for Talaash below: