Just read a rare book from 1933 called "Why we don't like people" by Donald Laird.
It lists the traits that make some people likeable and some people not, based on human psychology:
1. **We like people who like us.** If they like you, they have great taste, isn't it? So we like them back. This also includes sympathising with others and understanding their viewpoint. *(Is this one of the reasons why we like our parents? We know they like us. When someone likes us, we can't help but like them back.)*
2. **We like people who help us feel important.**
3. **We like people who buoy up our self-esteem**. It shows the faith and confidence most people have in themselves. They like other persons who do not shatter that self-ideal.
4. **We like people who let us talk**, or even encourage us to talk more. Their attention to what we say supports our self-esteem.
5. **We like people who do not try to change us.** As soon as they try to get us to stop smoking, or wear different clothes, they begin to undermine our self-ideal, and our liking for them is shattered.
6. **We like people who are cheerful**. Maybe they do not make us feel more important, but they do make us feel happier.
7. **We like people who cheer us up** by showing us the silver lining behind the clouds. *We like children because of their cheerfulness, their happiness, and their naturalness.*
*Caveat: Although we like cheerful people, we don't necessarily like jokers. Especially if the joke is at our expense and may tumble our self-esteem.*
tl;dr
A common thread we see in all these traits is that it boils down to making the other person feel important, to respecting their self-ideal, and to being a genuinely positive, cheerful person to be around.