If you're flying from outside the United States, you'll be arriving at JFK Airport in Queens or Newark Liberty across the Hudson River. The city's third airport, La Guardia, is used for domestic flights.

To reach Manhattan from JFK you may take buses that circle around all the terminals (taking about one hour), or a taxi that should cost anywhere between $35 and $50 (including toll and tip). Unless you're flying alone, taxi is the best option. Better yet is choosing a Shuttle Arrival Transfer or Shuttle Departure Transfer between any of the three airports and your Manhattan hotel.
Alternatively, you may also go for the special luxury of a limousine round-trip transfer.

If you choose not to go for any of the transfer services above from Newark's airport, take the free monorail from your terminal to the airport's train station, from where you can take a train into Manhattan's Penn Station (stopping at Newark's Penn Station first), with the journey taking about 20 minutes. Alternatively, you may choose a taxi that could cost over $50 and take anywhere between 40 minutes to one hour, depending on traffic.

If you plan to go up to the Hamptons or perhaps a trip to the casinos of Atlantic City, rent a car.