To extend user510's comment about using the first names: people who use the first name of their waiter are generally going to be the people who talk to your manager for the least issue. Having been a waiter in Western Europe myself, if someone I don't know were to call me by my first name, it would immediately put me on the defensive because of the likelihood that this person is going to take any less-than-perfect service as an offence. It's not a guarantee, but there is a general tendency. — Flater 2 mins ago