I do not recommend you do what I did and that is have a lousy experience with a tailor after giving him almost $5000.00 and then post about it here, then have a decent tailor contact you through the board (after he was given tailoring "advice" by the bad tailor) and then give the good tailor money to make you clothes. Its worked out well for me and in my opinion David Reeves Bespoke is about the best operation in New York City but I figured I would post about how to do it like a normal person.
Your first step will be to realize that New York City is filled with dodgy tailors who fake their own online reviews. It even has some good ones who also fake their own reviews to compete with one another. I am not going to name names but a search for reviews will reveal them. The ones that have the least filters (like google reviews) are going to be popular. Look for reviews written like advertisements. Citysearch reviews will sometimes have pros write fake reviews. You can tell this by how many cities they write reviews for and if the reviews seem skewed in some way (too many 5 star ratings over diverse topics such as dog sittng services, sushi, and escort agencies). Another one to look for is the negative review that say "Don't believe the positive reviews". Just one review like that may be expected since not everyone is pleased with service but if it happens every four reviews or something then you should be suspicious.
Finally look for reviews written in an accent. Many of the tailors here are not born in the US and they tend to omit things like helping verbs or use terms not commonly used by someone named "Mike" like "Happy Customer!" or "Very Happy With Suit" instead of "I am very happy with my suit".
In New York, faking reviews is so common it might not mean the tailor you are looking at is bad, he just thinks he is competing. So you have to look further.
To check more thoroughly you need to see how established this person is. Is there a name of a real owner? It might sound strange to those of you who are used to a business either being a faceless corporation but with a corporate HQ and a complaints & legal department or a small business owned by an identifiable person or family who has final say in its affairs and definite responsibility for the business, but with many New York City tailors this is not the case. They do not want their names to be known due to a previous bad reputation under another company name or perhaps for tax reasons. If their was a hypothetical tailor shop called Fantastic Awesome Tailors and their proprietor was listed as Bob Smith you should be able to check up on that name as a tailor pretty easily because Bob will not wish to hide. If the name is listed as Bobby S. then that should send up a red flag and you would want to avoid that tailor because getting your money back should something go wrong could be more difficult.
The next thing to check is location. Use google to check the address. Is the address a temporary office space that is rented daily or is it more established? A temporary office space may just be someone trying to remain mobile while saving money but I have not found that to be the case. I would avoid tailors that use a temporary office space simply because the company probably does not have enough capital and clout to get your clothes made and delays will be more likely to happen. Plus it is harder to sue a business located at a temporary office and the landlords tend to only care if their clients bill is paid on time, not the quality of their clients work. Plus you really do not want to strip down to your underwear to try on pants in some conference room that anyone can just walk into.
If a storefront location is used it is probably better but even if it is located within another company, like a drycleaners, then it could be okay too but I advise that you call the business that is located there and ask about the tailor. If they refuse to talk to you then something dodgy is going on and it is time to move to the next tailor. My tailor, David Reeves, works out of a well known cloth distributor's office so if he ran a shoddy business it would reflect upon them as well...but since he does not there are no worries.
The next thing to check out is their website or blog or whatever. Do they have their own photographs of their own work? If so, then good. Look at it and see if you like it. Do they have stock photography? If so then you have to ask yourself why a tailor would not have any photographs of his own finished clothes. Not everyone is a webmaster of course (though every small business owner should be these days) and not everyone can figure that stuff out or they had someone else do the website for them because they just cannot be bothered. The way to find this out is to just call and ask them if they have any photographs of their actual work. If they do then they will be happy to send it to you, if they don't or make excuses then you should move on to someone else. The other thing I look for on websites is their promotions. Do they offer things like three for the price of two? Or free shirts with full payment in advance? To me that sends up red flags but not disqualifying ones. I think a tailor should use their work and their service to promote themselves and should not rely on other advertising hooks.
The final step would be to ask your perspective tailor for references. Give him time to ask a former or current customer if you can contact them by e-mail. Some might not want to do this due to privacy concerns and the final choice should be yours but I feel that if they demonstrated a good effort to try to get them for you would be a positive sign. Most people I know are happy to vouch for a good business, especially one that is somewhat expensive since they also want the business that they enjoy to stay around, but perhaps I don't know what everyone is like in this city.
In conclusion the regrettable way to search for a tailor in New York City is to start out assuming they are shoddy and insist that certain criteria be met before you even consider them and begin to look at things like price and style.
Anyway, this is the tailor I use now and he is quite good. I will vouch for him and I am only doing this because of the relief I found by getting away from the dodgy tailors in this city using the advice above.http://davidreevesbespoke.wordpress.com/