PATH app can be helpful.

For cabs; try to hail one on a street (avenues at nights are packed), and simply ask if they’re willing to drop off in JC. I’d say i’ve been told yes maybe 75% of the time. Some cab drivers have a book in their glove box that list fixed-rate prices to specific areas (downtown jersey city, airports, stadiums, etc), so they’ll even discuss & agree to a flat rate before beginning the drive which is fair for both you & the driver. You have the option to say “no, thats too high” and get out of the cab, if you need to, as well