I am guessing from context you're an American going to Europe.

The US is big; distances in Europe is more manageable. However, we've packed a bunch of stuff into every square kilometre. Just because you can do Paris, Venice, Florence, Rome, and Naples all in a week doesn't mean you should. I lived a while in Florence, and I always overheard American tourists talking about how they "saw" all these great European cities in just a day before moving on. They didn't see shit other than the Eiffel tower and the Ponte Vecchio.

Find a place you want to experience, and try to actually experience it. Go to museums. Eat their food. Visit small unknown places. Walk around. Learn about the place.

Europeans don't generally love Americans. We mostly tolerate them. We kind of like their culture, but our favourite Western movies are Italian.

This is not an attack, but a fair warning. Don't parade how American you are expecting people to treat you better - the best you can hope for is that they'll expect you to leave a fat tip. Try to mimic social codes around you. Don't be the loudest person in around - and if the loudest people around you are Americans, they're either being obnoxious or you're in a tourist trap.

Don't ever brag.

Investigate when you can eat and what you can eat when. Lunch and dinner times vary from country to country and sometimes city to city. If you're hungry between 14 and 18 in France or Italy you'll be lucky if you can settle with a sandwich. Restaurant closing times vary a lot too - a Pizzeria in Italy will open at 19, in Denmark it will close at 20.

When in Rome and all that. Macdonald's might do in a pinch, but Europe is a continent of cheese, wine, beer, and regional specialties. Find out what people eat in the city where you are. You probably don't want to order a paella in Andalucia; only Americans order bolognese in Naples.

Especially in France, don't expect everyone to speak English. They might not be very comfortable with it, and starting a conversation in English an awful start. Learn a few phrases. In France, always start any interaction with a bonjour or bonsoir. At the very least learn how to ask people if they speak English in their own language. In many countries their response will be "of course I do", but chances are they'll still appreciate the effort.

And good luck!! It's a wonderful continent, especially if you're interested in art, food, or history.