At one time or another, each of us needs to be persuasive or convincing. You may be a professional salesperson. An entrepreneur. A manager. A parent.

Whatever the case, for most people, being persuasive is intimidating.

People stress about saying the right thing. About finding that one magical phrase to make people say yes. About not tripping over their words.

But science tells us a different story.

When it comes to being persuasive and convincing, it's what you don't say that matters the most.

Marianne Schmid Mast and Gaëtan Cousin, in the book Nonverbal Communication, have identified 15 science-backed behaviors used by persuasive people.

The good news? These are behaviors that any person can master, behaviors that, when paired with the most basic argument, will take your persuasiveness to the next level.

1. Speak faster (more than 150 words per minute)

Most people speak between 125 and 175 words per minute. The faster you speak, the more your perceived expertise and credibility increase.

(Just don't overdo it.)

2. Maintain eye contact

Never be the one to break eye contact first. Persuasive people keep eye contact longer.

3. Smile more

Plain and simple, people respond to smiling.

4. Use facial expressions

Facial expressions and animation convey passion and enthusiasm for your cause. It's not only contagious, but convincing as well.

5. Nod more

Subtle nodding triggers a subconscious, but positive, reaction in listeners.

6. Gesture more

Use your hands, a lot. Like facial expressions, hand gestures reaffirm passion and conviction, and increases your persuasiveness.

7. Lose your nervous ticks

Touching your face, wringing your hands, grabbing your ear, rubbing your eyes -- all these movements come across as suspicious. Avoid nervous ticks at all costs.

8. Use objects

While nervous ticks are out, nonchalantly playing with a pen or other object portrays an air of casualness and relaxation. That puts the listener at ease.

9. Don't lean back too much

While you want an air of relaxation, you don't want to be too relaxed. You don't want to come across as noncaring. You'll never convince someone that way.

10. Keep it close

Depending on your relationship, the closer you can get, the more convincing you will be. Sometimes it's OK to push the personal space limits.

11. Relax

People who are uptight come across as nervous, or having something to hide. Relax if you want to be persuasive.

12. Don't stand at attention

Speaking of relaxed, loosen your posture up a little bit. Being too rigid portrays an air of superiority and won't aid your cause.

13. Move around

Think about normal conversations. People move, change positions, sway. Keep your movements as relaxed and normal as possible.

14. Make physical contact

Again, depending on your relationship, a barely noticeable touch anywhere from the elbow to the shoulder of the other person before making your ask will make a world of difference.

Try it.

15. Don't overdo it

Don't speak too loud, or too soft. Don't be too animated, or too lethargic. Don't be too aggressive, or too passive. Practice keeping your personality in the middle when you need to be persuasive.