Italian eating rules: for breakfast you can have cappuccino and cornetto, forget about sausages or eggs
LUNCH AND DINNER
No butter should be served to spread on your bread (I think it takes away from lunch anyway - I do not serve it when I cook).
What about dipping bread in oil? There's no harm with this in the course of a meal, but the bread-oil routine is not used as an appetizer. It has a tendency to fill you up and diminish your enjoyment of the meal.
No bread should be eaten together with pasta. This is a major no-no. At home here in the US, we make fresh bread when guests come... and you know hot bread is very attractive... after learning that this is what Barbarians would do, I resolved to serve bread only after pasta is gone from the table. Bread is only allowed near a pasta dish to do a good old fashioned "scarpetta," that is, to wipe the sauce off the plate and enjoy every last bit of it.
Have mineral water and or wine with your meal. Forget sodas or milk unless you are a teenager or small child. Ok, an exception can be made if you are eating pizza at lunch time, in which case sodas are ok.
The Italian main meal is traditionally multi-course: restaurants like to serve you first and second plates and do not appreciate it when Americans insist on having one thing (although they have been getting more used to it in recent times). But keep in mind that Italian portion sizes are smaller than American's, and the mixture they serve (pasta/rice first, followed by meat/fish/vegetables, followed by fruit) is a relatively healthy balance. You may get fewer calories and a healthier, more balanced meal by eating three courses in Italy, rather than one, giant entrée covered with cheese in the United States.
Fish-based pastas: traditionally, grated cheese is not added to fish-based meals. These rules have eroded somewhat, but you may still get a strange look if you ask for it.
Coffee may be drunk with fruit or desert but never with the main meal. In addition, traditionally coffees with milk (cappuccinos and lattes) are for breakfast. Lunch and dinner are followed by espressos, or, at most an espresso macchiato (this is a rule that my wife likes to break, but she likes to live dangerously and can talk back in Italian if someone challenges her).
Contrary to the perception of some, cinnamon does NOT go on cappuccinos or lattes. Chocolate/cocoa or whipped cream does. Go with the flow on this one, you'll have fun