There is a thriving spotting community in and around the NYC area. Feel free to e-mail me at firstname.lastname@example.org if you'd like to talk.
As for advice on how to "begin", check out Art Brett's website anniebees.com, which has some useful information for spotting locations around JFK
has some great spots, too, but I can't think of a website off the top of my head that has a list of spotting locations. Unfortunately, I don't know too much about EWR
since I have never actually gone there for spotting.
Anyway, like I said, feel free to e-mail me if you'd like to talk more.
One more thing...check out the Aviation Photography forum, which is where you should probably post this kind of message. You'll get lots of responses there.