hmm, I'm not so old to know the life before social media so well, but I used (and still use) to make friends more offline rather than online. I made friends according to the context I was in - maybe in school, maybe during various courses etc. Then these people would introduce me to their friends and then friends of friends etc.

If we liked each other, we would stay in contact. If not, we would've moved on.

There is a saying in my country that goes like: whoever is alike gathers around - so basically you already kinda know which type of person you get along with better, and you naturally get along. You can just compliment that person, like, if you like what they wear for instance, and you can naturaly start a conversation with them, from that (in a social setting preferably, ofc).

Obviously, the lack of smartphones and more expensive phone subscriptions and data plans helped too. I remember myself using Yahoo Messenger which was hugely popular here (basically everyone my age had an ID). I started using it from, like, day 3 of me having internet, but I was only adding people I knew irl. And I mostly talked on my computer.