“Say hi to everybody” works great. I used to just “hang around town” late at night, bored. I’d be friendly to everybody I met – sometimes just a quick look in the eye and friendly smile. Next thing I know, I’m at a party with people. Hardly know how I got there.
Of course those were events that had drinking / drugs / dancing / sex / whatever. Most weren’t long lasting friends but a couple I’m still friends with today through facebook.
I made lots of ‘strangers on a plane” friendships taking bus trips places. All I had to do is look friendly, say “hi” and the next couple of hours of the trip I learn everybody about somebody and at the end, we part ways, never see them again but a fun experience.
Never liked dealing with people that were already in groups though. Had to be people who were alone or with one other person at most. Once there were 3 or more people, I’d steer clear. They usually had a weird vibe. But individuals are usually individual because they’re in the same boat as you so they’re usually receptive at least to be a ‘strangers on a plane” friend at least.
Forgot about doing that stuff tbh. Did a lot of embarrassing stuff which is why I try not to remember — but I did as soon as Jeff said “say hi to everybody” – I remembered Always used that trick at workplaces. Perfect for making “let’s go to lunch” friends.