I always have a few euros or pounds,) whatever currency used in the country to which I am traveling ) on hand before I travel. I try not to change money in the airport if at all possible. As soon as I get to my destination I find a bank with an ATM and use a debit (or cash) card to make my transaction. more times than one I have asked a taxi driver to take me by an ATM. I find I routinely get the best rate that way.