When you exit the terminal, look for the nearest taxi stand (our taxis are yellow and easily visible). The line is usually across the street from where you exit the building.
Be aware the cost is a FLAT RATE in the amount of $45 (no more than $50 with any authorized additional charges) from JFK to anywhere in Manhattan.
Travel time will should be less than 30 minutes without traffic.
Do not accept a ride from the men who stand outside offering taxis. They are illegal, they rarely leave right away and instead wait around to fill the car with as many people, and customers report of excessive charges.
From JFK to Manhattan