> I have zero idea how to make small talk with people I haven't known for years.

Forget small talk.

Listen-- really listen --and engage with open ears. When it's your turn to talk, offer up an anecdote in reply if it's on topic or take the opportunity to pivot to a related topic you're passionate about. If you do the latter: do. not. info-dump. Give them a chance to play the game I just described to you from their side.

Need a cold opener? Get the party going with something you anticipate the majority of the people there would remember.

--

You: "Hey, does anybody remember the Blizzard of '96?"

Them: "Yeah! I remember they closed down all of Route 9!"

You: "Hell yeah they did. My family pulled me down the highway on a snow tube. I've gone tubing every year since. Any tubers here?"

Them: "No, but I love snowboarding."

You: "Nice. I was briefly obsessed with snowboarding after playing 1080 on the N64, but I was always too chicken-shit to try it. Where do you go snowboarding?"

Them: "Vermont. Where do you go tubing?"

You: "I used to do it over near that big hill by the library. Ever see that?"

--

Arm yourself with personal stories to make situations like this easier. People would rather interact with the guy always telling stories than the visibly-uncomfortable one sitting in the corner.