You don't have to open your mouth to say something. Often, your body says more than your words ever can. Perhaps more than you'd like, your body language can reflect quite accurately what's going on inside you.

I recently attended three trade shows in three days, and what I learned about myself surprised me. If the representative in the booth was looking down at their phone, didn't acknowledge me, or made eye contact but didn't smile I tended to shy away from their booth. It didn't matter if the product would have been a good fit for me, I was instantly turned off.

On the other hand, if the representative was too eager, it was also a red flag. What worked best for me at least was someone who acknowledged my presence, and smiled. It was welcoming, but not too aggressive. We weren't wearing name tags or badges at these shows, so it's important that you treat everyone similarly, you never know what opportunities you might miss simply by being too busy checking social media.

What does body language encompass? It includes body movements and gestures that we make with our arms and legs, hands and head, and even the way we position our body and our posture.

For example, a slouch can make you seem lazy and lackadaisical, while good posture might make you seem more confident. Most people know these signs. But did you know that your muscle tension, eye contact, and even how fast you breathe, how often you blink and the way you sweat makes an impression on other people?

Different things are perceived differently between different cultures and even people within those cultures, but there are some general impressions that are quite universal. Here are seven ways that negative body language can impact your work, and lose you clients:

1. Watch your handshake.

How much pressure should you use? Avoid the "dead fish" handshake, which makes you seem like less than a player than you are, but don't crush your client's hand with a death grip, which makes you seem aggressive. Aim for a firm handshake.

2. Beware of the signs of lying.

Experts have been studying signs of lying for years and years. Everyone is different, of course, but signs can include little or no eye contact, talking with your hands in front of your mouth, keeping your body turned away from others, rapid breathing, and complexion color changes.

I have a friend who always rubs his nose after he lays a ridiculous story or "new business venture" on me, and every single time I think, "Wow, he's lying to me right now!"

3. Shutting off your body from others.

When people feel negatively about something, they may cross their arms or position their body away from others. They might clench their fists or hold their arms stiffly when they are stressed or angry. These self-protection signals can make others not trust you, or like you less because they don't feel that you are entirely open to a situation.

4. Superiority positions.

When a man sits back in his chair with his hands behind his head, it's a superiority position or a management pose that makes it seem like he is trying to intimidate a subordinate, whether he intends to or not.

This is something that you want to avoid if you are a man, especially if you are meeting with clients. People are turned off from those pose. Instead, try leaning forward to make people feel relaxed and liked.

5. Eye contact.

Eye contact is something you have to be careful about. Too much can make others feel that you are staring them down, and too little makes it seem like you are not confident enough.

6. Watch what you do with your hands.

Fidgeting makes you seem like you lack confidence, or that you are nervous. If you put your hands in your pockets or keep them under your desk, it makes you seem like you are hiding something. That makes potential clients feel like you aren't telling them everything.

So what to do with your hands? Keep them in full sight at all times and facing upwards. If you talk with your palms down, you're seen as authority, and some people can feel intimidated.

7. Watch what your face is denoting.

Men and women construe things differently. It all depends on who you are listening to. If you're listening to a male, limit the expressions on your face. If you're listening to a woman speak, mirror the expressions on her face to seem more empathetic.

Don't forget to nod when speaking to people. Nodding encourages people to talk more and share more information. It also shows that you're paying attention when they're speaking.