You would hire a broker to find exactly what you are looking for so that you aren't running all over the city seeing things that you know you wouldn't like. One wouldn't necessarily have the time search for available apartments and look at them with a full day of work so it's easier to hire a broker. And you never if you are dealing with a real person or a scammer on Craigslist especially if there is no phone number. It's definitely better to use a broker knowing that you will actually have an apartment as opposed to getting scammed out of a few months rent and no apartment.
You may be able to find an apartment where the owner may help with the broker fee but that really depends on what you are looking for.
If you do decide to use a broker, send me an email email@example.com or call me 646-243-4516 to discuss your rental further.
You can always go online to Rent.com and list your property for rent but what about 1) Credit check 2) Screening 3) Application 4) Letting a stranger into your home? Agents take a lot of flack for pursuing that commission, but agents really do have the hook up (meaning they are well connected)!
All the best,
Alajuwon J Aleem
Douglas Elliman Real Estate
firstname.lastname@example.org (646) 915-5979
If you are asking in general, then the best place to start would be looking in he free online ad places along with local pennysavers, newspapers, etc...
your local newspaper
Tammy Hayes, Realtor
Re/Max Palm Realty