We may indeed initially judge a book by its cover, but we don't stop there. Certainly, beauty may be the first thing that attracts us to a person or object, but other factors make us attractive too. Most notably, people are also attracted to personality.
Some of the most notable research supporting the role of personality in attraction comes from the evolutionary psychologist David Buss. For example, in 1986, Buss and Barnes surveyed both married couples and unmarried individuals about their preferences in a mate. The researchers asked about whole host of characteristics, including physical attractiveness, personality, behaviors, resources, and status.
Married couples were particularly asked about the characteristics that they found attractive and valuable in their own partners. Out of 76 identified characteristics, all of the top 10 related to having a warm, positive, an pleasant personality. Traits such as being a good companion, considerate, honest, affectionate, dependable, intelligent, kind, understanding, interesting to talk to, and loyal.
For single folks, personality characteristics were also the first three chosen out of 13 larger personality dimensions. Those dimensions were kind and understanding, exciting, and intelligent. Of later importance was also easygoing and creative.
Beyond being attractive in its own right, personality characteristics also change other people's perceptions of our physical appearance. This effect was studied by Lewandowski, Aron, and Gee in 2007. The researchers also used both men and women as participants. In this study, however, they provided false personality information about students, paired with their yearbook photos. Participants were then asked to judge the physical attractiveness of the students based on the picture and description.
The authors found that pictures paired with positive traits were rated as more beautiful/handsome, and those paired with negative traits were rated as less attractive, when compared to controls. This effect occurred with pictures of both "attractive" and "unattractive" students. This effect also happened for both men and women participants, with women a bit more sensitive to negative personality information. Finally, the effect also influenced judgments of desirability as a dating partner.
In summation, personality counts for a lot. Particularly, being positive, kind, exciting, and intelligent can go a long way to attracting others to you. So, make sure to put your best foot forward.
The third law of attraction is proximity, read about it here.