Let your credit card company know your travel plans

If you are planning a trip to Italy, or any country for that matter, it is important to call your credit card company prior to your departure to let them know of your travel plans.

That way, if you use your credit card overseas, the transaction will go through.  If not, the credit card company may not process the transaction, or may try to get your authorization.

The credit cards widely used in Italy are Visa, Mastercard, and American Express (in that order).  Discover is not widely used, and thus you can pretty much leave that one at home.