Church (genuine suggestion for anyone) We often have non Christians turning up to our church for one reason or another. A non Christian comes every week because he loves the people. You can find churches with members on either side of the political spectrum if you worry about that.

One thing I love is that (almost) wherever I am travelling in the world, I can just turn up to a church and feel welcomed.

My wife and I moved to a new city and went to church and were invited to a family home for dinner straight after the service. It's great to experience that in a city where you don't know a single person.

As an atheist (raised Catholic), I can recommend Unitarian Universalist congregations as generally very welcoming and friendly places. They're pretty common in the northeast US at least.

You've gotten the standard responses already: Join a social club. Play a sport. Go to meetups. These responses are not wrong, per se, but they're one step divorced from the deceptively simple looking actual process of making new friends, which is this:

Find people to talk to, and talk to them often. The ones who you like talking to and like talking to you will end up your friends.

That's all there is to it, but like you already know it's harder than it looks, because the problem is finding like-minded people to talk to, and that's why you're getting a bunch of advice about hobbies. Turns out that people who like certain hobbies tend to enjoy talking about them with other people who enjoy those hobbies. It's a proxy for an easy conversation.

Those who find it harder to have conversations with strangers will find it harder to make friends, so try to teach yourself that skill, because at some point it's all down to being a numbers game.

Join local interest groups. Even if they're only online. Creative hobbies, foods, sports, religious/philanthropic groups.

Be proactive, even/especially if you're an introvert and it feels awkwardly forward. Most extroverts have already formed their fill of friendships by their 30s so you can't rely on them to initiate anymore. And people are more socially flexible/accepting than you may think, and welcoming of human interaction.

Give more leeway for who you consider "friend" material than you would in younger years. It's easier to find someone who's generally cool to hang out with but only has a couple interests in common, than someone who shares your exact set of interests but is easy to get along with. E.g., neighbors are a good place to start. Even if all you have to talk about is the neighborhood, if they're not a colossal asshole, they'd probably be a cool person to grab a bite to eat with once a month.

Don't plan for attachment. Expect that you might just grab lunch a couple times with someone, and they or you might move, have a kid, turn out to be a colossal asshole, etc., and the friendship drops in priority. If you get really invested early on, you'll get burnt out quickly by this.

Same advice applies to rekindling old friendships. Check back in with people you knew from college who were cool but you lost touch with. Maybe they live in the area and would like to catch up, and maybe they happen to still be a cool person and have a new interest which matches a new interest of yours.

It is hard during the pandemic.

Got a hobby? I bet there's a club that meets semi-regularly. For example the original D&D generation is well past their 30's, so I'm sure you could find a group that meets every could weeks with lots of players in their 30's, at a local game shop. Similar for boardgames. Or if you have a hipster coffee shop nearby it might have a corkboard up with slightly less nerdy version of this stuff.

Hard to do it without an existing connection to be honest. I'm not sure if all the "join a hobby group", "play a sport" etc. responses actually work for people, but they definitely don't for me.

Plan a picnic or hike and hit up old Facebook/LinkedIn contacts who are living in the area, or ask existing friends to bring along their friends/coworkers.

Make a decision to be 'all in' on doing it and being genuinely interested in people.

That might mean finding venues where you're statistically likely to meet people who you will find interesting. However, don't judge a book by its cover. It'll definitely require putting yourself out there. If that worries you, it gets easier the more you do it. I can't stress enough that you're going to need to mentally "burn the boat" and have total commitment.

I know that lockdown is currently a hurdle, so maybe think about where you could go once things open up. Meetup.com is a great place to start.

Also consider using lockdown to be more interesting yourself. Learn something you've always wanted to learn. Try reading 10 books on one subject.

When I moved a few years ago, I became friends with a few folks from my new job. This is something I explicitly did not do in the past. Other friends have come from my college alumni club and pre-pandemic activities.

I joined a weekly game night. A lot of communities prior to pandemic) had weekly board game meets. In Sacramento, there is BoardGames and Brews weekly meetup. I'm sure similar kinds of things exist elsewhere.

Have you tried making enemies instead? Then you can befriend their enemies.

Take up an outdoor sport / fitness activity - and join a local club.

You make friends by being places where other people are and having something in common you can talk to them about.

Pick up a hobby where you interact with other people. I ride mountain bikes, but there are lots of options. Look for clubs which might interest you. Or go back to school part time.

All of this is near impossible in COVID times. Get vaccinated, wait until group meet ups are common again.