It's difficult, but the biggest barrier is money. If you bring a lot of it to the table NYC is not a huge pain to rent in (less so than SF, actually).

Some basic issues:

- 40X Rule. As a rule of thumb, your rent multiplied by 40 needs to be less than your annual pre-tax income. Failing to meet this means you're probably not getting the apartment, or if you do, you'd be expected to pay a huge deposit, or in some other way mitigate the landlord's risk.

- Brokers everywhere, and on the whole they are extremely corrupt. In NYC it's very rare to contact an actual landlord through a listing - you're contacting a broker, who will expect a commission of 12-15% of your annual rent for the privilege of being allowed to rent this apartment.

- Every channel where a renter might contact landlords directly and cut out the broker middleman is flooded with deliberate spam. Bait and switching is common - where they list on a "no fee" listing site, but when you call the apartment "suddenly rented" but there is a broker-fee apartment still available at the same address...

- Obfuscation is common. Some apartments are exclusively represented by a brokerage firm, where they've come to some arrangement with the landlord. Other apartments are actually fee-less. Brokers will attempt to suppress these apartment listings from getting out into public view, and repost them instead as "their" listings. The easiest way to recognize this is when the posting refuses to reveal the exact address (instead they will list nearby intersections).

- More bait and switch: brokers will frequently try to upsell with fake listings. This is common done by either posting a very good-looking apartment at a great price, and then arrange the showing. Once you actually show up to see the apartment they will try to pivot you to another, more expensive apartment that you didn't sign up for. This is also frequently done by showing the actual apartment, but relabeling it to be in a more desirable area. You can often tell this is happening if the broker refuses to meet near the listing's location, and instead tells you to meet them "by their office" in a nearby, but less desirable, location.

- Unlike most aspects of NYC life, there is no effective police action against the above abuses. You can file a complaint with the real estate licensing body, but unlike, say, the taxi licensing body, no real consequences result for the cheating broker.

- Terminology bingo. NYC is very space constrained, and as such landlords and brokers alike have come up with specialized language to describe their apartments that make them sound better than they actually are. Learning to read between these lines is a pain. A "flex" 2-bedroom actually means a 1-bedroom apartment where a makeshift living space has been constructed in the living room (this can be anything from a semi-legitimate wall to a curtain). A "1 bedroom" is frequently just a plain lie, it's a studio apartment. "Charming" usually means run-down. It takes quite some time to really figure out the hidden meaning behind a lot of apartment postings.

- Fake apartments altogether. This is particularly true if you're young, not used to renting (even in other cities), and trying to rent without being in the city to look at places. Lots of places will collect rental application fees and then reject all candidates. Rinse and repeat. Warning sign is an abnormally high application fee.

- Quality of landlord. Sometimes even good-looking apartments are actually run by slumlords who won't fix the heat, won't fix the water, and generally let everything go to shit. Because most NYC apartments rent in a matter of days (if not hours), there is no ability for the renter to do due diligence on the landlord. This is changing - the city has made building complaints public via API, and more and more real estate sites are incorporating this data.

- Simple noise. This is a real tragedy of the commons situation. Most listing sites are filled with duplicates as one broker tries to out-spam the others. Brokers also spam listings across unrelated sections of sites in the hopes of getting a hit (relabeling a studio as a 1-bed, a 1-bed as a studio, posting it in a different part of the city, etc). Stale listings that no one has bothered to remove. It goes on.

If that hasn't scared you away yet. Welcome, have fun :)