I've been listening and reading up on the mystery method lately and the part that I can't get is openers. Usually when I'm already in conversation I feel comfortable to joke, be playful, tease, push/pull etc. I'm getting better with all that, but horrible at finding good reasons to start conversations with strangers and not make it obvious I'm not intentionally opening them. It's really hard to think of things, most people don't have anything interesting about them at first glance.

How can I get better at this so I don't keep freezing up and sitting there like a moron not talking to anyone?