I allways carry two credit cards and two debit cards. I used to call my banks before travelling, but I no longer do that.
We travel often enough and our banks are aware of that.
Carnival Liberty New Year's Eve 2007
Liberty of the Seas 5/2008+11/2009
Allure 1/16/ 2011
Independence of the Seas 12/29/2013 Booked!