What are the most common tourist mistakes I should avoid?
First and biggest mistake: not buying tickets in advance. Make sure to plan ahead and skip long waits under the Roman sun. Also, don't try to hail a cab in the street, there are designated spots for taxis. Coffee-wise, keep in mind that cappuccinos are reserved for breakfast, so instead try ordering un caffè or un caffè macchiato after noon (if you ask for a latte, you'll get a cold glass of milk).