Once you arrive at Suvarnabhumi Airport, follow the signs leading to Immigration. On the way to Immigration, you will see a sign “VISA on Arrival”. They are big and clear so you will definitely not miss them. You will pass ATMs and currency exchange booth of Siam Commercial Bank on your way. If you don’t have enough Thai baht for paying Visa on Arrival fee, you can exchange your currency at this booth or at one of the booths located just near the entrance to Visa on Arrival section.