An international travel card is the most secure option for paying while travelling abroad. Niyo Global is the best Travel Card that you must add to your list. It is an international debit card that helps people make payments in more than 150 countries hassle-free. I am also using Niyo Global Card, The Best Card i recommend..
I prefer to use US Dollar in abroad. I visited Singapore, Malaysia nd Indonesia nd use US dollar. I change US currency into that particular Country's Currency.
Once I got a bad experience in Rome. I got robbed at Metro Station. My bag was stolen and all the documents were gone. After that, I decided to keep some amount of cash and card as well. Don't carry a huge amount of cash with you keep it safe in the hotel's locker. There are many money exchangers available at the airport. So I get my money exchanged for them when needed. For every location, I think you should carry both types of payment modes.