Your chariot will be labelled Havatas. Ask at the information desk in the airport and they’ll direct you if you’re not sure where to go to catch this bus, but it’s just outside the airport exit.
The service is very regular, leaving every 30 minutes. It starts at 4am and the last bus leaves at 1am. The journey takes a reasonable 40 minutes, but obviously consider time for traffic.
Additionally, the service I used to get to Taksim didn’t leave on time and whenever people showed up as we were about to leave they’d wait and take them on. Good news if you’re running late, bad news if you need to get going, so bear that in mind. I didn’t buy a ticket in advance and I think because I landed so late (23:30), it wasn’t much of a problem to get on the bus.
It cost 11 Turkish Lira, an awesome, pocket friendly price if you have a tight budget or just want to save some money. When I asked around, a taxi would’ve cost about 50TL. If it’s a few of you then a taxi may be worth it. It might also cut your time down a little because unlike the bus, you won’t have any scheduled stops on your route.
The Havatas bus service also runs from Taksim to Sabiha Gökçen Airport, as well as a few other routes. You can get more details of them here http://www.havatas.com on their website.
This was a life saver for me. My friends who I met up with in Istanbul joined me on it as well when we departed. They used the metro when they arrived and with their baggage it was a struggle fest! Hopefully this saves you some money and backaches too.
Happy & safe travels!
~~~The Wandering Pier