In France, I always thought it was customary to leave the change from l'addition. (I'm not French though, so perhaps I was commiting a faux pas)

I can confirm in Italy almost no one will even accept a tip. (Taxi drivers, wait-staff, hotel staff)

> leave the change from l'addition

Yes, that is the basic tip if you expect to come back to that restaurant and get an upgraded welcome.

But even with no tip, being a regular counts - tip or no tip, you are good business and worth cultivating.