Making friends anywhere and everywhere.

30M, was wondering if it’s possible to become friends with strangers and ask for their number after meeting them for the first time and after having your first conversation. How do you know when you feel the vibe to ask and how do you go about asking it? How do you go about making conversations with them when you don’t know what to talk about? I want to make friends anywhere and everywhere, whatever it is me waiting in the grocery line, in the airport, out at a restaurant or bar, or talking to a worker on a movie theater, etc. How do I do this? What are some inappropriate topics to discuss? For most of my life I have been very shy.