While Mastercard and Visa are globally accepted, I'm sure there are other credit cards one can use abroad to shop, pay for stuff etc but I don't use those. From what I've heard, using these cards attracts a fee of 3% [exchange costs] each time you use the card. . .so are there any credit cards you can use and avoid getting charged this fee?
As much as possible I really avoid credit cards when traveling abroad. I have made that anyway. There interest rate is just crazy. So unless it's an emergency, I ain't pulling out my Visa.
I find that HSBC is the most reasonable when it comes to charges and fees. They are also accepted globally. I think it works the same way for Citibank, although I often really just use HSBC. I also find their currency conversion rates to be very considerate.
All cards have some sort of fees when using them abroad. It's only logical since your bank has to pay these fees so they charge them from your account. What I like to do is pay with cash when traveling. I can use my visa card to take money out of the atm (just have to estimate the rough amount I'll need for the trip because each time you take money there is a charge) and then pay with cash where ever I go.