Cash And Carry France I'm Going To Europe And I Was Wondering What Is The Best Form Of Money To Have?

I'm going to Europe and I was wondering what is the best form of money to have? - cash and carry france

I come from the U.S., and I'm in England, Ireland, Amsterdam, France and Italy, and I wonder what is the best form of currency that during his visit. Do I need to replace a credit card or traveler's checks or cash before you go here, or is it something along the lines of a Visa debit card can I get? Any information would be appreciated.