Cultural norms can vary drastically from country to country, and even among different regions within the same country.
Take Italy for example. The South is a little more laid-back, and has a few particular traditions and superstitions not commonly found in the North. For example, it's considered back luck for four people to shake hands at the same time - forming a cross. Many older Italians will wait until the first party is finished shaking hands before putting forth their hand.
This tip and many others you can find on GotSaga.com - World's Most-Visited Countries - Travel Etiquette. Author Lee goes through 8 popular travel destinations and names some of the most relevant cultural etiquette you'll want to know for your next trip. Check it out!