1. When visiting mosques, cover your legs below the knee (long capris are minimally acceptable) and medium-length sleeves. Head scarves in mosques are optional but respectful, and there are always spare ones inside. Shoes must be removed.

2. In the countryside, men should not approach women, even to ask for directions.

3. Shorts are okay on or near the beach only, but this isn't necessarily a religious thing: "In Turkey, like anywhere else in Europe, the big cities have big-city dress codes," says Serhan Güngör.

4. Don't compliment a man's wife on her appearance unless you know the family quite well or they are clearly urban and secular.

5. You'd be hard-pressed to find a totally dry town (other than a rural village), but outside the largest cities many restaurants do not serve alcohol.

6. Men and women don't usually kiss each other on the cheek, although people of the same sex do.

7. Women should dress relatively modestly for solitary walks through Istanbul—for the reason you'd do so when alone in New York or Rome late at night.

8. In hammams, men never completely expose themselves to other men; towels will be provided. Even during a massage, don't take yours off. Women don't have the same taboo.