Learn from my mistakes.... :)
#1. Don't assume all pizzas come with a tomato sauce base. If you don't see the word "pomodoro" in the description, you're most likely going to get a white pizza. BTW - "pomodorini" refers to sliced cherry tomatoes.
#2. "Peperoni" are bell peppers, not the spicy salami we get in the USA. If, like me, you despise any kind of bell peppers, you will not have a pleasant pizza experience. :) Look for "salamino picante" or some kind of similar wording if you're looking for the meat version.
#3. There are no doggie-bags. Most people get individual pizzas, though sharing is not frowned upon. Look around at the pizzas your fellow diners are eating. If it looks like more than you can eat, see if someone will share OR if they are willing to eat what you can't. It is not good form to ask for a box to take home leftovers. Italians just don't do that. But really... come on, the crust is uber-thin, toppings are not too abundant - are you sure you can't eat it all?
#4. No free refills or ice. If you're ordering a soda, water, lemonade, etc. don't expect it to contain ice. it will be very cold but ice is drinks is not "normal" here. (something about drinks being too cold & impeding digestion i think? whatever) Also, there are no bottomless glasses , if you wan't a refill, be prepared to pay for it.