Some have it. And some don't.
That ability to engage people in conversation. I don't have it, so I consulted an expert today!
He's very good, just like some other people I observe.
They have this innate ability to start talking to people, in queues, in lifts, at supermarkets, in parks.
My expert pointed out to me that you need to pick something about the other person that you notice. Their tie, maybe they're wearing a badge, their hairstyle, what they're wearing. In fact, most people by what they wear, are making a statement, and spotting that statement and asking about it, is a practised skill.
So for your homework, go away and observe a few people and work out what statement they're making, and if you're really brave, ask them about it (The thing they're wearing, not the statement they're making!!)
And say something like, "That's an interesting tie, where did you get it from."