Also, if you want to pay cash, or need cash before leaving the airport, there are ATMs after you leave the customs area, to the left, and then you can go reserve your taxi on the opposite side (post-customs) of where the booths are on the inside. (That doesn't make sense, I know - but the taxi service booths have a dual counter - one to the left as you are walking to the customs exit, and one, if you loop around to the left after you leave customs.