Researching your travel locations can be very exciting. Use reliable travel books such as the “Lonely Planet” guide to fine out what type of local food is available. They also have a great section on the main types of food which is usually in English and local language, which you can then photocopy. You can then identify what food is gluten free and highlight that food. This then acts as a quick reference in your wallet when you are out and about.
This book gives a quick reference to the main gluten free food available in all different countries and translates the fact you require a gluten free diet and have the need to avoid wheat, rye oats and barley etc. You can photocopy the phrases (for the countries you are visiting), laminate it (to credit card size) and then place it into your wallet. When ordering food either in a restaurant or street vendor show them your card. It helps when you can not speak their language. Test it out on some people who can speak the specific language in your home country before you travel, just in case it is written in a dialect that is a minority within your travel destination.
It's not fool proof but does help. I try to get a person from the country I am visiting to read the card before I travel to ensure it is easy to read and understand. Sometimes they can have too much information which can be confusing. I am heading to India soon, so the card has been shown to an Indian gentleman. He has made a few “local' changes that will help as India has many different dialects. So change your card as required.