six universal principles1.  Reciprocation:  People like (even feel obligated) to return favors

2.  Authority:  People tend to look to experts for guidance. This can include precedent.

3.  Commitment/Consistency:  People like to feel that they live and act in accordance with their values, that they keep their word.

4.  Scarcity:  We tend to want what we can’t have. This makes the “fading or limited time offer” effective. In other words, “That which we obtain too cheaply, we esteem too lightly.”

5.  Rapport/Liking:  If we like or care about others, we want to please them, say yes to them. People like to bond, to belong.

6.  Social Proof:  The behavior of the group frequently guides individuals’ behavior. We look to others for clues on how to react.

Source: “Influence: Science and Practice,” by Robert Cialdini

Closing quotes:

“You don’t have to be a ‘person of influence’ to be influential. In fact, the most influential people in my life are probably not even aware of the things they’ve taught me.”  — Scott Adams; 1957–, Dilbert cartoonist

“The humblest individual exerts some influence, either for good or evil, upon others.”  — Henry Ward Beecher; 1818–1887
“It takes tremendous discipline to control the influence, the power you have over other people’s lives.”  — Clint Eastwood; 1930–