If you are planning to arrive to Sabiha gökçen airport we recommend you take train as it is fastest and easiest method.

You can use public transport to reach pendik train station the bus number is 132H check timetable in here https://iett.istanbul/EnRouteDetail?hkod=132H You can use your contactless cards for public transport.

Also, you can use taxi to reach train station 

More information about train: http://anadolu.esnturkey.org/train

You can also choose to take bus but there is many different bus station in Anatolian side of istanbul and most of the bus companies only stop at one of them you can check attached file for learn how to reach them 

There is also shuttle bus to Bursa (one of the biggest cities in Turkey) bus station.  https://bus.burulas.com.tr/en/Bus

More information about bus http://anadolu.esnturkey.org/bus