You have the option of taking a taxi (of course) and if you’re going to do that, then this will be useless. However, if you’re not in a rush to get into town and want to save some money, the Aerobus is the way to go.
First after exiting the baggage claim area, you’re obviously going to be spit out into the arrivals hall. You need to first get your Red Bus card. To buy one, you need to go UP the escalators (yes to the departures level) and as you get to the top, look to your right. Right next to the escalator is this newsstand /snack kiosk called Chammas. You’ll buy and load your card here (incidentally, if you already have a Red Bus card, you can reload it with funds at a kiosk on the arrivals level or at the Chammas.
Now it costs 120 pesos for the card and then 72 pesos for the bus ride. To make it even, I just got it for 200 pesos (about $5 USD). I paid with cash but I believe you can also pay via credit card if you don’t want to go to the ATM at the airport.
To get on the bus, exit the terminal building. You’ll immediately see a (small) row of taxis. The bus stop is on that same island but further down on the right. You might see some people sitting and standing near a blue sign with an airplane on it and a red 25 under it. That’s where the Aerobus shuttle will pick you up (and drop you off if you need to take it back to the airport).
The bus is supposed to come every 30 mins but it can run late. I think it was running more than a little late because a few people just gave up and got a cab instead. I’d say I waited around 20 mins or so for the bus to arrive.
Once on, just tap your card on the machine next to the drive and you’re on your way. However, the driver doesn’t announce any stops nor does the bus have any signage to let you know which stops are coming. It doesn’t even tell you where the stops are. So my advice is have your phone open to Google maps and just watch it for when the bus approaches your destination. If you’re within a few blocks, you’ll just want to press the button to let the driver know to get off at the next stop. Otherwise, he’ll just take you all the way to the bus terminal.
Using the Aerobus is pretty painless and fairly easy once you figure out where to buy the Red Bus card. I was walking around and asking everyone since I thought it was an actual store I needed to go to and not some newsstand-looking place. It’ll obviously take more time to get into town but you’ll save a ton vs. a taxi.
To get back to the airport, you’ll have to ask to find where the nearest stop is for the Aerobus and just wait. However, I would strongly advise you to give yourself plenty of time to get to the airport (maybe plan on getting to the stop 3-4 hours before your flight). I’m sure the schedule that wasn’t followed into town is probably not going to be followed on the way out. If the bus is my only option, I usually take it into town but then get a taxi or something else to get back to the airport. I just don’t want to gamble with possibility of missing my flight because the bus didn’t arrive on time.