I spent 20 years as an FBI Special Agent trying to get people to confess their crimes. I learned over the years that suspects more readily confess to people they like, and, as with most people, suspects do not want to be told what to do or think. Persuasion is a powerful interviewing tool because suspects decide themselves, and are not coerced, to take a course of action.

Later I found that persuasion plays a critical role in personal relationships and business relationships. Whenever two or more people get together to complete a task, whether it be a social actively like picking a restaurant or being part of team, there is always the possibility of an argument instead of agreement, which is where the power of persuasion comes in. With persuasion, there are no winners or losers. Persuasion is the art of getting others to do what you want them to do because they want to, not because they are forced to. And it can be tapped using these simple techniques.

1. Spend time with the person. 

Time is a powerful persuasion technique. The more time we spend with others, the more able we are to influence them. Time promotes trust. If parents want to influence their children, they should spend time with them. If workers want to influence their colleagues, they should spend time with them. If you want people who dislike you to like you, spend time with them. Eventually, they will like you--or at worst, they will dislike you less.

2. Be likable. 

People tend to help people they like. Getting people to like you instantly is as easy as displaying an eyebrow flash, a head tilt, and a smile. Restaurant wait staff tend to provide better service to customers they like. People who handle complaints tend to be more responsive to people they like. People are more likely to overlook mistakes, make exceptions to the rule, and go out of their way to accommodate people they like.

3. Change their minds before they say no. 

No one can read minds, but you can come close by observing a person's mouth. The lip purse is a slight puckering or rounding of the lips. Pursed lips mean the person you are talking to has formed a thought that is in opposition to what is being said or done. Knowing what a person thinks gives you an advantage. The trick is to change someone's mind before he has an opportunity to articulate any opposition. Once a person expresses an opinion or decision aloud, changing his mind becomes more difficult due to the psychological principle of consistency. People tend to remain consistent with what they say, but not with what they think. If you see pursed lips, you will know what someone is thinking and can use persuasion to change that person's minds before he says no.

4. Don't stop at "You're welcome." 

When thanked, most people respond, "You're welcome." But to make your response more powerful, add, "I know you would do the same for me." This invokes the psychological principle of reciprocity. When people are given something tangible, or even something intangible such as a compliment, they are psychologically predisposed to give something in return. Reciprocity increases the probability of compliance to future requests.

5. Add a sense of wonder. 

Introducing a sense of wonder in conversation or in the form of self-talk also increases the probability of compliance. People typically want to tell others about their expertise. Introducing a sense of wonder takes advantage of this tendency. If you need help with a task, seek out a person with that skill and, during the course of your conversation, simply muse, "I'm working on this project and I'm having some difficulty. I was wondering if you may have run into the same problem." An expert in the field will have difficulty not volunteering his expertise, just to show his mastery. He may even offer his services to help you solve the problem. This creates the illusion that the expert is offering expertise and not being requested to provide advice or free services.