It really all depends on what area you want to concentrate on. I live in New York and actually work in Manhattan, and let me tell you, you can get away with getting a lot done as long as you know how and when to avoid the crowds! A few more tips:
- Visit the popular attractions/places on weekdays, as early as possible.
- If you have a few days to sight see, be sure not to cram it all into one day. A lot of the attractions are far apart from one another. Budget your time for each geographic area separately. This will save you unnecessary bus/subway time (subway's are fast, but you can always get hit with delays, especially on the Yellow line), or worse, some absurd cab fare. The meter still runs, even if you're in traffic! For example, if you're going to see the Statue of Liberty, maybe don't do it the same day you visit the Empire State Building or Central Park, as they're all on the opposite sides of the city.
- If you're going to need the subway or bus (which I'm sure you will, at some point), avoid rush hour (5-7 pm)! Some subway lines are way more crowded than others, but it's best (in my experience) when you're trying to get everything out of the city to already be in the general area of where you're exploring by this time.
If you had any specific areas of the city in mind and had any questions, feel free to let me know and I'll do my best to answer them! Hope you have a safe and awesome time, and I'm sure I'll see you when X finally comes around here!