Within a fraction of a second, people will make a snap judgement about you based on your body language, says Mark Bowden, human behaviour and body language expert at Truthplane in Toronto.

Your “primitive brain” — that part of the brain that helps you avoid danger by decoding whether you should approach or flee — quickly makes a judgement based on body language. The primitive brain then sways the “smart brain” — your centre of logic and reasoning — to justify that snap judgment.

Once a person has developed a bias, Bowden says, he or she will look only for data that confirms their assumptions. For example, if a prospect interprets you as a risk based on your initial gestures, he or she will look for elements during the conversation that prove you’re a threat. While the prospect may not actually run from the room, he or she is unlikely to sign on as a client.

Here are three tips for making a good first impression:

1. Make yourself visible
If somebody can’t see your body, then it goes without saying that they can’t interpret your body language. By sitting behind a large desk or table, Bowden says, you’re providing clients with insufficient data about your feelings and intentions. By default, the client will form a negative impression.

Try holding meetings at the corner of a table, Bowden says, so you can maintain a view of each other’s physical gestures.

2. Hold your smile
Most people know that smiling signals good will toward another person. But a smile won’t appear genuine if it lasts only for a brief flash.

“The smile has to be sustained for more than three seconds for the primitive brain to register it as a true smile,” Bowden says. Otherwise, the other person won’t interpret the smile to indicate that this is a positive relationship.

“The client’s primitive brain will make a decision that there’s more risk than reward in the relationship,” Bowden says.

3. Avoid “closed” body language
If you’re sitting or standing with closed fists or crossed arms, people will read your demeanour as cold or distant. To appear warm and receptive, try to maintain open body language.

“Imagine warming yourself by a fire,” Bowden says. “You would open up your hands, chest and stomach area.”

However, keep your open hand or palm gestures near the height of your navel in order to appear engaged, calm and assertive.

“If you do these open palm gestures below the beltline, it can look indifferent or sometimes aggressive,” Bowden says. “And if you bring your hands up to chest height and do open-palm gestures, it can look a little bit too needy or too excited.”