How do I become closer with potential friends?

I’ve been talking to people lately— and I realized, I unintentionally talk to others I want to be friends with, as someone who wants to talk to someone temporarily and then never see them again. I can talk to people to start to get to know them but I don’t know how to cross the line of acquaintances into friendship. I don’t know how much I can share without oversharing, so I completely avoid talking about myself sometimes. I think this makes me seem very untrustworthy. It feels like I am running away from these opportunities of friendship. Is there a way to fix this?