Why are some people an absolute joy to be around? After a few conversations or moments of small talk, you feel you've established trust and some level of compatibility with them.

Here's what they're doing that others aren't: Reinforcing and nurturing rapport through their attentiveness.

During my time as an FBI agent, this kind of rapport-building was a crucial skill to have, particularly when conducting investigations, developing sources or just working with other agencies.

We tend to think of rapport-building as something we only do once, perhaps when we first meet and get to know someone. Not so. Rapport-building is something that exceptional individuals do every time they interact with others.

As a human behavior researcher, I've found that the "agree and add" method is one of the most effective ways to help people feel more comfortable opening up to you.

How to be smooth with small talk

Basically, it works like this: The person might say, "This commute sucks!" To which you say, "It really sucks," and then add, "especially when there's an accident."

With that single statement, you've let them know that you're listening, that you validate, and that you get it.

You, or the other person, might also respond with a related topic ("I started listening to this podcast about [X] to make the commute less painful..."), a funny story ("The other day, I was dropping my kids off at school, and [X] happened...") or question ("How's your summer so far? Did you get to spend time with the kids?") — allowing the conversation to continue and develop into something that's more interesting, mentally stimulating and fulfilling.

Another example: Someone says, "He's such a know-it-all." To which you reply, "He is, isn't he? He always has to have the last word." This is a simple repetition of what was said, with something small added that lets them know you understand and are in sync.

When I used this technique with my sources, it would get them to like, trust and feel more at ease with me, thus feeling as if they can open up and be honest.

It's also so much better than if you were to say "yeah" or "uh huh" or just give a few silent nods. Sure, sometimes an affirming nod works fine. But for validating others' thoughts and feelings, agreeing and adding works best.

How to disagree: Agree, add and affirm

Incidentally, this doesn't mean that you can't disagree. If you're completely opposed to something someone says and find it objectionable, feel free to express that.

But there's a way to do it with nuance. As with before, you agree and add something — but then affirm your own thoughts or convictions on the matter.

It might sound like this: "Yes, commuting really sucks, especially in the winter." Then, after a few seconds, you affirm: "But to be fair, it's remarkable how they keep the roads open after a heavy snow."

Or you could say, "I agree with you. The commute stinks and it's a big hassle. But it's certainly better than last year at this time."

Showing that you're listening to and acknowledging someone's words doesn't always mean bowing to everything they say. There's a place for your own take, and it's how you demonstrate sincerity and authenticity.

But for the sake of harmony, it's wise to agree, add and affirm.

I know wonderful, intelligent people who just don't understand this, and they end up bringing pleasant conversations to a halt by pedantically correcting a minor detail or by outright disagreeing.

Conversations are so much more successful and collaborative when we allow everyone to feel they can talk about and share ideas. You don't need to always correct or edit what others say. If you continually object to what people say, they'll eventually grow tired of interacting with you.

It's more than just small talk

You can also apply this communication strategy with deeper, serious and longer discussions.

Remember, rapport-building always starts at an emotional level. The implicit message you want to give is: "What you are experiencing right now is important to me. And I'm going to meet you where you are emotionally so that you know I am one with you in thought and sentiment."

Joe Navarro retired from the FBI after serving as an agent for 25 years. He has been studying nonverbal behavior for more than 45 years and is the author of 13 books, including "Be Exceptional: Master the 5 Traits That Set Extraordinary People Apart," "What Every Body Is Saying: An Ex-FBI Agent's Guide to Speed-Reading People" and "The Dictionary of Body Language: A Field Guide to Human Behavior." Follow him on Twitter @NavarroTells.

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