What's the best transport to use from the airport to the metro train to take south

Monorail

Take NJTransit Newark Airport to New York Penn Station take taxi to grand central terminal metropolitan transportation authority metro north

The monorail works to get me to some NJTransit trains.

Good morning Christine, if you're in terminal C outside there's bus stops which there's a bus for $15. Will take you to NYC BUS STATION where you can get a train to wherever you need to go. Whatever you do, don't get one of those yellow cab. Better the bus.