There's another aspect that I've learned is important as well. Characteristics that you don't have. Probably chief among those is that you don't make the people you talk to feel bad because of the way your own insecurities manifest.I think I know what people want from friends, the ability to be cool, the ability to make them feel safe, the ability to make them feel wanted and desired, or the ability to make them laugh. On the other hand you can have the ability to appear plain alongside them in a nightclub, the ability to lend them money numerous times, the ability to pay for meals etc.
Not bragging or putting others down to feel better about yourself. Not pointing out the negative aspects of everything because you're feeling negative. Not trying to one-up every story someone tells.
And so on.
[This is not a commentary on you, or anyone in particular]