• Think of the building staff — My super once complained to me about inconsiderate tenants who would throw dangerous things like broken glass or knives away and just toss the garbage bags out like normal trash, which often led to injury on the part of the building staff. Just because something's left your possession doesn't mean that it's disappeared. I asked how broken glass or similar objects should be disposed of, and she said I should put the garbage bag into a cardboard box and write "Caution! Broken glass!" on the box.
• If you've got a good super, don't attempt to do their job — If you are lucky enough to have a great super and building staff, let them do their jobs.
Once there was a hair clog in my tub that would not go away. Not wanting to bother the super, my husband and I tried bleach, Liquid Plumber, a plunger ... when those didn't work, we Googled, "How to fix a clogged bathtub" and started following random Internet instructions. Four hours later, I gave up and called the super. She arrived to see parts of the plumbing I didn't know existed stacked up all around the bathroom. "Oh my God!" she said. "What did you do!?"
• Do not adopt upholstered sidewalk furniture — One of my neighbors once decided to give a sidewalk futon a good home, despite Manhattan's notorious bedbug epidemic. The results were predictable. Everyone on the southern end of the building was infested.
• Mitten the kittens — One night a downstairs neighbor came up to complain about constant stomping late at night that was keeping him up, even though my fiancé and I had been sitting on the couch for approximately four hours straight and certainly hadn't been stomping or even stepping. I was confused until he left, when both my cats vroomed under my feet like a set of tiny, furry train cars. I couldn't stop them, but I could put down rugs and stack boxes like speed bumps to slow them down.
Be aware of what causes noise in your house: TV shows, Dance Dance Revolution, high heels on wood floors. Your neighbors and roommates (even romantic roommates) will thank you.
• Everyone makes mistakes — Even though I fixed the cat problem, I was terribly embarrassed every time I saw that neighbor in the hall. My embarrassment persisted until he accidentally set the building on fire, and then I figured we were even.
Part of being a good neighbor is recognizing that everyone messes up sometimes. If the gaffe is yours, correct it and move on. If it's someone else's, let them know politely, then forgive and forget (unless they bring bedbugs).
What have we missed? Add your tips in the comments.