Every twirl of your hair, crossed leg or micro-expression gives off a message. Learn how to take control over how people view you.

Say please and thank you. Don't raise your voice. Sit up straight with your legs together and hands on your lap. Don't draw attention to yourself. And never ever brag.

These are the lessons many parents teach their daughters. And while these attributes--politeness, deference, humility--and the way they are projected through our gestures, gait and self-presentation can certainly help in the classroom and certain social settings, they could be holding many of us back professionally.

Jeannine Fallon, executive director of corporate communications at Edmunds.com, learned this at a training course called "Women Unlimited," which she attended when she worked at Volvo 10 years ago.

"I distinctly remember one insight," she says of the session. "At a boardroom table, women tend to pile all their materials neatly and sit tucked into the table, while men tend to sprawl out, push away from the table, cross his ankle over a knee and lock arms behind his head. It was impressed upon us that the concept of taking up space correlates to the concept of dominance." The result? "I've never sat tucked into a table since."

An image is worth 1,000 words: No matter how illustrious our resumes, how brilliant our ideas, how Calvinist our work ethic, we are judged by how we present ourselves. Research shows that it takes four minutes to make a first impression, and, according to a widely cited study by UCLA professor Albert Mehrabian, body language accounts for 55% of that impression (38% comes from tone of voice; the remaining 7% from our actual words).

Unfortunately, says Carey O'Donnell, president of Carey O'Donnell Public Relations Group, based in West Palm Beach , Fla. , "many of us have no idea that our non-verbal cues are making an impact. There are thousands of micro-expressions, and people are reading these, even if they are only subconsciously translating these cues."

Some of the visual ticks common to women:

Tilting your head - A sign of listening that can be misinterpreted as one of submission or even flirting.

Folding your hands on your lap - Hiding your hands under a conference table or desk, for example, signals untrustworthiness; a cue from ancient times, when men would reveal their palms to show they were unarmed.

Crossing your legs - A sign of resistance.

Excessive smiling - An indication that you lack gravitas and seriousness.

Folding your arms in front of you - Translates to insecurity or defensiveness.

Playing with or tugging at your hair, jewelry or clothes - Can signal distress or, again, be misinterpreted as flirting.

Many of these habits are deeply engrained and, even when we think we have expunged them, tend to flare up when we are in stressful or nervous situations.

"For example, when there are only men at a meeting and one woman, the woman tends to get nervous," says Carol Kinsey Goman, executive coach and author of The Nonverbal Advantage. "Because they are larger and take up space, men have an imposing, assertive demeanor. And that can be intimidating."

"Women are much more expressive than men," she adds. "Men have more of a poker face, and it drives us nuts because we can't read what's happening--we don't know where we stand. … And when we keep explaining a point and see no reaction, we tend to panic and overdo it to make case."

So, how do we mitigate these ticks if we aren't even aware we are doing them?

"A mirror can do a lot," says Kinsey Goman. "Practice your speech a variety of ways--with your head tilted, your head straight--and note the difference. Practice your gestures. Gestures are terrific but don't do them above the shoulder--you'll look too erratic."

O'Donnell also recommends videotaping presentations and then watching them without sound. "When we see ourselves in pictures, or especially on TV, we often say, 'Who in God's name is that?'" she laughs. "When you watch yourself without sound, pay attention to visual cues--are you waving your hands frenetically, laughing inappropriately when no one else is laughing, looking around nervously? Then watch it a second time for voice tone and bridges [such as] likes and you knows."

As for dealing with nerves beforehand, Theresa Zagnoli, founder and CEO of Zagnoli McEvoy Foley, a communication and litigation consulting firm, recommends shutting the door of your office or retreating to the restroom and taking 10 to 20 deep-belly breaths. Another trick: releasing nerves by scrunching your toes--an act that, unlike fiddling with your hair or retreating back in your chair, will go unnoticed.

Zagnoli also preaches a tactic called "mirroring."

"The idea is that the more like the person you're dealing with you can become, the more you will connect," she says. "Is the person you are sitting across from soft-spoken? Does he or she speak slowly, smile and laugh a lot? Is their pad on the desk or their lap, do they take notes copiously, are their legs crossed, are they leaning forward or backward? I take note of all these things and then chameleon myself to become more like that person."

Some businessmen and women balk at this idea--or at the idea that we have to transform ourselves in order to get ahead. But, assures Zagnoli, it is not a compromise. This--the mirroring, the mimicking and the suppression of bad habits or impulses--"doesn't change who you are," she says. "It doesn't change your heart, what is in your head, your ideas. In fact, changing how you carry yourself allows us to communicate those thoughts and feelings more fully."