You just have to do two things:
1) Be the best human being you can possibly be, and
2) express genuine interest in other people.
I've seen my dad putting these two points into action over the years, especially at dinner parties or on family vacations. Take tonight for example. We were strolling through some night market streets, and my dad goes up every other booth -- with no intention of buying anything -- and starts asking about the products, the seller's background, and other random things. Soon, he's laughing or teasing everyone around the booth, and then we either have a discount on the product or a smile on our faces. It's a win-win.