5. Make friends with their friends
The social-network theory behind this effect is called triadic closure, which means that two people are likely to be closer when they have a common friend.
To illustrate this effect, students at the University of British Columbia designed a program that friends random individuals on Facebook. They found that people were more likely to accept their friend request as their number of mutual friends increased — from 20% with no mutual friends to close to 80% with more than 11 mutual friends.
6. Don't be complimentary all the time
The gain-loss theory of interpersonal attractiveness suggests that your positive comments will make more of an impact if you deliver them only occasionally.
A 1965 study by University of Minnesota researchers shows how this theory might work in practice. Researchers had 80 female college students work in pairs on a task and then allowed those students to "overhear" their partners talking about them. In reality, experimenters had told the partners what to say.
In one scenario, the comments were all positive; in a second scenario, the comments were all negative; in a third scenario, the comments went from positive to negative; and in a fourth scenario, the comments went from negative to positive.
As it turns out, students liked their partners best when the comments went from positive to negative, suggesting that people like to feel that they've won you over in some capacity.
Bottom line: Although it's counterintuitive, try complimenting your friends less often.
7. Be warm and competent
According to the model, if you can portray yourself as warm — i.e., noncompetitive and friendly — people will feel like they can trust you. If you seem competent — for example, if you have high economic or educational status — they're more inclined to respect you.
Harvard psychologist Amy Cuddy says that, especially in business settings, it's important to demonstrate warmth first and then competence.
"From an evolutionary perspective," Cuddy writes in her book "Presence," "it is more crucial to our survival to know whether a person deserves our trust."
Kevork Djansezian/Getty Images
8. Reveal your flaws from time to time
According to the pratfall effect, people will like you more after you make a mistake — but if they only believe you are usually a competent person. Revealing that you aren't perfect makes you more relatable and vulnerable toward the people around you.
Researcher Elliot Aronson first discovered this phenomenon when he studied how simple mistakes can affect perceived attraction. He asked male students from the University of Minnesota to listen to tape recordings of people taking a quiz.
When people did well on the quiz but spilled coffee at the end of the interview, the students rated them higher on likability than when they did well on the quiz and didn't spill coffee or didn't do well on the quiz and spilled coffee.