Good day Buon giorno (used all morning until just after lunch)
Good evening Buona sera (used after lunch through the evening)
Good night Buona notte
Excuse me Permesso (when leaving a bus, etc)
Excuse me please Mi scusi, per favore (when some inconvenience has been caused)
I beg your pardon Chiedo scusa
Thank you Grazie
To solicit a kindness or respond to Grazie Prego (meaning I pray, like the old English “prithee”)
To call a waiter Prego, or the slightly less polite Senta
To order from a menu Vorrei questo... (I’d like… and point at your choice)
Finally, do not mumble. Italians will understand anything if it is said with volume.