First impressions count; they are the gate through which you gain admission to the most important relationships you will have in your life, professionally and personally.

Human beings are like heat-seeking missiles when it comes to establishing someone's character, values, and sincerity. We can't help it, we're wired to connect. So while a true relationship is built on years of trust, the foundation for that trust starts in the first seven seconds of meeting someone, according to clinical psychologist and author of Straight Talk, Linda Blair. It's taken you about three times as long to read this far.

That's not much time but it's what you have. So how can you use it to make the best possible first impression, and then how do you build on those first seven seconds to make it unforgettable? It's amazingly simple and straightforward. Here are six proven ways to make an unforgettable first impression, whether you're doing it one-on-one, to a small group, or even an audience of thousands.

1. Know who you're talking to.

Well before those seven seconds, do your homework. That might mean a little research or simply observing a person's surroundings. When I first met Larry Elison, Oracle's Chairman and co-founder, at his home, a full-scale reproduction of a Japanese fishing village, I began by asking him if the tranquility and beauty of his home provided respite from the many demands on his time. That launched us into a conversation about everything from how he loved to play acoustic guitar on his porch, to his kids, to the modest beginnings of Oracle. Sure, I had done my homework, but that quick connection turned what was supposed to be a 30-minute meeting into a two-and-a-half hour genuine and authentic connection.

2. Eye contact.

The single most telling behavior that signals sincerity is making and maintaining eye contact. Few things are as unnerving as trying to have a conversation with someone who is periodically glancing at everything going on behind and around you. Our serotonin, oxytocin, dopamine, and endorphins (the feel-good chemicals that give us a sense of well being and euphoria) all increase dramatically when we look someone in the eyes, and they look back. Do not lose eye contact during those first seven seconds. However, this is not a staring contest. Also engage through conversation or it just feels contrived and creepy. By the way, if you're doing this with a large audience don't just stare out at the crowd. Combine looking at all parts of the room with direct and regular eye contact with individuals. That combination will put you at ease and create a much more intimate setting for the audience.

3. Mirroring

Mirroring is the simple act of paying close attention to the person you're with and adopting the subtle nuances of their body language, the tone of their voice, even the words they use. This is not mimicry, which is a caricature of a person, but rather the ability to empathize. Think of it as tuning into their frequency. To hear someone, and to have them hear you, you need to be sensitized to the way they express and absorb knowledge. Simple things like mirroring their body language can signal coherence. Don't discount this one, it is among the most inherently human ways we connect.

4. Active listening.

Being an active listener means understanding the person you are talking to before you try to have yourself understood. The temptation is to define ourselves before we fully understand someone else. Try repeating what that person has said to make sure you have heard it. It may feel awkward to you but you'll be amazed at how well people respond when you make the effort to understand them first.

5. Using the person's name.

This is a no-brainer and yet so few people do it. When someone calls us by name there is an immediate heightened awareness of that person. Don't say his or her name in every other sentence, but use it immediately after you meet them, at least once during the conversation, and at the close of a conversation. If you have a hard time with names use the person's name in context as soon after the start of the conversation as possible. That will reinforce your own recollection and show an immediate interest in knowing them on a personal level.

6. Being grateful.

Never walk away from a first encounter without doing three things; thank the person(s) by name for their time, sum up the value of the conversation, and add a personal comment that draws on a nonprofessional aspect of the conversation. Showing you recognize a person for who they are means you're interested in them.

Each of these can be misconstrued as techniques to simply charm. But if that is in fact your only goal, then beware of using any of these unless you are extraordinary well versed in the art of acting and theater. Sincerity cannot be easily feigned; it either exists or it does not, and it starts in just seven seconds.