Don’t talk “random people in public places” — head out into the world, and and engage with the world. There will be some people in those places, and some of them might seem cool or interesting, so say hello — or do something nice for someone. If they appreciate what you said or did, they might continue to engage further. Over the course of days or months, you’ll be talking with friends in public.

The point being the goal isn’t to corner a random person like a dating match. Be organic and open, and in time you’ll end up where you wanted to be.