I'm not perfect at it, but what helps me is that I genuinely love to learn and I like to take the opportunity to learn from people when I meet them. I just need to find an entry point (job, hobby, something the person is knowledgeable about) and then I start asking questions, and applying the limited knowledge I might already have on the subject.
With short interactions with people that are working (supermarket, bank, restaurant, phone assistance) I usually go for empathy, and overall just being nice. When one comes to me I go for a joke to brighten their day a bit.