Call your credit card company

If you are going to be traveling in an area that you do not normally make purchases in, you want to take a few moments to contact your credit card companies and let them know.  This will hopefully prevent their fraud department from flagging your account, and stopping charges from going through while you are away.

Also look on the back of your card and make note of the collect phone number.  This is the number you will want to write down, and keep in a safe place for travel overseas.  The 800 number will not work overseas, so this is how you will get in touch with your credit card company in the event your card is declined, lost, or stolen.

Keep in mind that your credit card credit limit is in US Dollars.  In recent months many currencies, including the Euro and Great British Pound, have become significantly more valuable than the dollar, so your credit limit will not go as far.  Look at exchange rates before you travel abroad to see how far your money will go.