The advice I give many family members and friends who will be traveling overseas is to take at least two credit cards and at least two ATM cards AND a small wad of cash.

One credit card should have no forex fee (like CapOne) and should be used for everyday purchases. The other should have good international customer service (like Citi or Amex) and should be used only for emergencies. If you truly don't trust your teenager with a credit card, then don't bother with the low-fee one--just give him the backup one, since the customer service will matter more than the fees if he's only using it for emergencies.

One ATM card should have 0-1% forex fees and preferably rebate ATM-owner fees (like many credit unions and online banks) and should be the primary way to get cash. The other should use a different network (i.e., if the main one is Visa/Plus, get a second ATM card on the MC/Cirrus network) and doesn't need to be no-fee since you'll mainly use it for backup in case the primary one doesn't work.

Still bring enough cash that you can buy food and pay for lodging for a week if the various cards don't work for some reason.

For advice on the fees of various credit/debit cards, see our wiki:

http://flyerguide.com/wiki/index.php...reign_Exchange