Le samouraï (1967)

Being cool, for dummies:

1. A cool man doesn't need to say he's cool.
2. He don't have to speak at all.
3. Whether it's about love or murder; he never admits a thing.
4. But always makes sure his hat sits properly on his head.
5. He buys newspapers to look inconspicuous.
6. Changes subway trains at the last moment, to lose possible tails.
7. Makes sure to be seen at certain places, to secure alibis.
8. He remembers that charm can be a powerful weapon.
9. But never trusts a woman.
10. Last, but not least, he makes sure to see this film, or risks being double-crossed.

IMDB