What I actually do now and what works are different things. I have a low social battery so after work, wherein I have to engage with people I normally wouldn't all day, I'm tapped out. When I get home I get in my pajamas and that's it. Which makes me pretty lonely.

So right now I am trying to arrange my lifestyle so that I don't have to work full time and have more energy to actually regrow my friend group which has crumbled over the years.

But, for advice:

Sometimes I will go to a local coffee house. For the price of a drink you can hangout for a long while. Take something to read or draw on. You can listen to headphones or not. I've also seen people crocheting and playing board games.

You don't have to talk to anyone, you can just sit around people and sometimes that helps me just feel a little more connected to society in general. And unlike a lot of places, it's fine to start a conversation with a stranger there, which is generally how a lot of friendships begin.

Often places have a board up where people pin fliers about events that might interest you. Like a detective looking for clues to their next adventure.

If you find a spot you like make it a commitment to go frequently. You will get to know the regulars and the staff.

Over all, though, unlike being in school, once you are an adult it takes work and commitment to getting your social needs met. You have to go to the events and meet the people and spend effort to build relationships with them.