Growing up in a tiny, dot-on-the-map town in rural Missouri, Dale Carnegie was a “skinny, unathletic, and fretful” son of a pig farmer, writes Susan Cain in her book on introverts, Quiet. After observing a charismatic public speaker traveling through his hometown, Carnegie, despite his innate introversion and with much determination, became a speaking champion and leader himself.

He eventually launched the Dale Carnegie Institute, devoted to helping businessmen overcome their insecurities. Though published in 1937, his book How to Win Friends and Influence People remains one of the best motivational books in history, addressing a question that’s core to everyone’s existence: How do you get along with people?

Carnegie identified a few major recurring characteristics or habits of highly influential people, from Abraham Lincoln to Thomas Edison to Charles Schwab. Time-tested to this day by current leaders like Oprah Winfrey, these habits are still widely relevant and apply to practically every industry and relationship.

Read on below to learn three fundamental traits in people who successfully handle others.

THEY DON’T COMPLAIN, CRITICISE, OR COMPLAIN.

“When dealing with people, let us remember we are not dealing with creatures of logic,” writes Carnegie. “We are dealing with creatures of emotion, creatures bristling with prejudices and motivated by pride and vanity.”

Criticism, he advises, can strike people’s emotions, causing them to give up—even driving them to suicide.

“Any fool can criticize, condemn, and complain—and most fools do,” writes Carnegie. “It takes character and self-control to be understanding and forgiving.”

Instead of condemning your children, your direct reports, your teammates, your family, or your friends, Carnegie says, “Let’s try to understand them. Let’s try to figure out why they do what they do. That’s a lot more profitable and intriguing—it breeds sympathy, tolerance, and kindness.”

THEY GIVE HONEST AND SINCERE APPRECIATION

The big secret of dealing with people, Carnegie points out, is recognizing that everyone is driven by a desire to be important, to be appreciated, and to be great. This is echoed in the theories of many philosophers, from Sigmund Freud to John Dewey.

Even Lincoln recognized this: “Everyone likes a compliment,” the president once began a letter.

How we get our feelings of importance is one significant factor in what distinguishes us—for some it’s driving the latest car, for others it’s making an impact in our childrens’ lives, or it’s being recognized for our philanthropic efforts. Many people will go to great lengths (crime, insanity) to achieve this feeling, so

“imagine what you and I can achieve by giving people honest appreciation,” Carnegie poses.

As Charles Schwab, one of the first-ever millionaires in business, put it,

“I have yet to find the person, however great or exalted his station, who did not do better work and put forth greater effort under a spirit of approval than he would ever do under a spirit of criticism.”

THEY AROUSE IN THE OTHER PERSON AN EAGER WANT

As Harry A. Overstreet wrote in his book Influencing Human Behaviour,

“Action springs out of what we fundamentally desire… and the best piece of advice which can be given to would-be persuaders, whether in business, in the home, in the school, in politics, is: First, arouse in the other person an eager want. He who can do this has the whole world with him.”

For instance, Carnegie tells parents, “If you don’t want your children to smoke, don’t preach at them, and don’t talk about what you want; but show them that cigarettes may keep them from making the basketball team or winning the hundred-yard dash.”

He advises,

“The only way on earth to influence other people is to talk about what they want and show them how to get it.”

The most influential people are those who can find a way to relate their own goals to another person’s perspective and personal goals, inspiring others to take action in their own self interests.