Now that I'm at a computer, I'll add more:
135 Ave at 132 St (Morning if they're landing on 13L)... it's in a neighborhood so you might want to lay low at this spot.
"Mounds" location: 149th Ave at 230 Pl (Afternoon 22L arrivals)
"DHL Lot" definitely stay in your car at this spot. I wasn't hassled, but then again I was spotting from my car. You can park up against the bushes.
147th st @ Cargo Plaza
JFK is not the most friendly place to spot, but if you use common sense you'll be fine. Just remember it's not illegal to take photos of aircraft in public places. If you have a security officer or cop stop you, be polite and try to make it clear it's a hobby/passion. Most of the cops are just fine, the security at the parking garage is a different story. You can read up on them at nycaviation.com