What interests you about people
I think that building and maintaining friendships might be founded on a general interest and curiosity of one person towards another.
Maybe I'm always too concerned with myself to be able to think of the other person. But if I manage, on occasion, to pry my thoughts away from me, what should I find interesting about the other person?
Do I look for similarities and/or differences in personality and interests? Do I look for characteristics that I admire in the other person? And there must be some kind of interpersonal magic that people use to suss out these characteristics in others. I mean, they can have what appears to me to be a boring casual conversation, yet they appear to have gotten some deeper meaning out of it. And when I try to achieve meaningful conversation, people look at me like I'm speaking a different language.
So what draws you into another person's life? What interests you about a stranger, enough that you would seek social engagement with that person. How does one make social interactions meaningful and supportive, or at least, make them seem less of a burden?
Anything worth doing is worth overdoing.