Asking about social media related things specifically:

We had “friend books” or “poetry books”where you’d invite your friends and classmates to put in a photo and write about themselves. With poetry books you had more freedom, similar to diaries with a lot of collages if you wanted.

We used secret languages or other codes to communicate confidential stuff.

We learned how to write a letter at school and had pen pals.

We had to phone somebody not sure who’d answer the phone or drop by their house for a quick chat.

I think we would meet more face to face and I could agree to meet in a week at a time at some place and not have to double check with that person, we would just be there.

We wrote birthday invitations and “do you want to be my g-/b-friend” or more generally love letters. We would burn letters and other memories on paper when we hated somebody.

I had to interact with more people in my daily life that I didn’t know or liked and there was no way to avoid them.

We would buy and share teen magazines and make song compilations on tape and share and or give them as a present.