What I do is if someone is doing something interesting, I just walk up and start talking to them about it. Like if someone has a stranger things t-shirt on, I just think of ways I know about the topic, and then I slowly transition to a similar topic, like TV shows or movies. I like to use humour to get people to relax themselves, so think about what type of person you are and try to play it to your personality. It took me a year to finally get comfortable engaging in regular conversation, and the thing is, the more you do it, the more knowledge you gain from other people to talk about (like a snowball effect). It may feel awkward and you won't want to do it because humans only want positive feedback, so train yourself to be happy just to have spoken to someone, even if it didn't go as planned.