I live in Italy and here it's quite common so I usually don't have problems. There are gluten free restaurants, my friends understand what I mean when I talk about contamination. But I'm Bulgarian and there it's totally unknown, people even don't know what gluten is! Even doctors sometimes don't understand and people usually think I'm just making a strange diet. I usually try to explain but it's not easy because everybody thinks you are exaggerating and don't understand the damage of eating contaminated food. What I do there is try to cook for myself if possible, for example if my cousin invites me for dinner I go first so we can cook together so I can check everything. If someone offers me something I usuali ask something to drink (tea, coffee, coce) or a fruit . At the restaurant I usually take a salad or some meet explainig my problem (even if it's embarrassing sometimes). In Italy, Germany, Spain it's easy, here we have some apps so you can find gluten free bars and restaurants.
Good luck!
And remember, always bring some gluten free food in your bag when you go out :)