Imo it doesn't matter if you live in a luxury high rise or a shitty college apartment: I highly recommend gifting homemade cookies or some sort of sweet treat to your nearby neighbors. Tbh you don't even have to look face-to-face at them if you're too anxious: you can just knock on their door, set the plate down (with a note explaining why it's there ofc), and scurry off and it'll all be fine
I recommend this because honestly: we don't know our neighbors anymore, and it's really lonely and isolating to not know them. I don't think there's any need to be best friends with them, but to establish a sort of "hey idk you that well, but I'll look out for your shit if you look out for mine" kind of relationship can go a long way. And I think sweet treats are a great way to break the ice and everything bc hey, we all gotta eat somehow