Good omens and red flags
When you finally find your castle, your palace, the apartment of your dreams, just make sure you do one last surveillance sweep of the grounds before you sign on the dotted line. You want to make sure you're committing to a good landlord, one who will fix things in a timely fashion, respect your space, and deal with you honestly and fairly. Look and see: are the appliances in good shape? Are the hallway and stairwell well-kept? Are there mousetraps or any holes from which other "tenants"—a.k.a. vermin—could crawl out? No landlord is perfect, but if the apartment is shabby when you're about to sign for it, odds aren't good that it will be getting much better once the deal is done.

Also inquire about the safety of the neighborhood. Do a little investigative reporting. Most local newspapers do features on city life in different neighborhoods… make sure you and your new hood are made for each other. If you are on the fence about safety, stop by a local police precinct to get some information from the cops; some police officers on the job might exaggerate and make things seem a little worse than they are, but they do it as a precaution. Also look to see what businesses are on the blocks between you and the nearest public transportation stop/garage/parking spot. Conventional urban wisdom maintains that the safest neighborhoods are those where there's street life; old timers on the stoops, kids on the corners, even patrons of bars and bodegas open late into the night are all "eyes on the street," looking out for others.