Many travelers have the expectation that Europe will be just like their home country, except that people might speak a different language. While ideas are converging and becoming "global," there are still some major differences that the first-time traveler to Europe should know about.
Remember--it's not difficult to deal in generalizations--it's difficult not to find fault with them. Western Europe is a big place and it's been settled over its long history by lots of different cultures. So take the generalizations below as general guidelines for navigating European customs. Sweden is vastly different from Portugal. That's what makes travel fun.
The idea of the "big gulp" cup or infinite refills of soft drinks that you've come to expect in the U.S. has not exactly caught on in Europe. Do not expect to ask for a refill of your beverage and not be charged for it. Also, the price of American-style soft drinks is often high with respect to the price of beer and wine. Just remember our own Thomas Jefferson, who was an enthusiastic observer of European customs: "No nation is drunken where wine is cheap and none sober where the dearness of wine substitutes ardent spirits as the common beverage."
Drinking wine or beer at tables in the streets is more common in Europe than it is in the US. Despite this, European driving laws are constantly being revised to redefine impairment levels downwards. If you are driving, check the allowable blood alcohol levels in the country you're visiting - you might be surprised, given the availability of wine and beer.
Then there are the one liter (34 ounces) beer glasses of Bavaria!
High, but often hidden. You're paying a hefty tax for that lunch on the terrace, but it's unlikely to be broken out on the bill.
Tipping is a minefield. For western Europe in general, tips represent more the spirit of the true tip - that is, it's a percentage of the bill you give for good service, not a large sum that goes to pay the wages of your server. Unfortunately, as Americans bring their customs to Europe, the expectation of a large tip is increasing as wages for servers decrease, especially in large cities.
Voltage in Europe is twice what it is in the US. Most computers and modern techno-stuff operate on both voltages, and only an adapter plug is needed. Beware that not all European plugs are the same. Older hotels may not have the juice to run that 1000 watt hair dryer you desperately (don't) need.
Shop the Local Way
It is customary to greet shop owners in their stores in many European countries. If you're planning on doing shopping in small boutique type stores, learn to say, "good morning" or "good afternoon" in the language of your destinations. You'll start to find shopping easier and more pleasant - and you might catch a bargain along the way. Folks are generally highly appreciative of any attempt you make to speak their language and learn their customs and using a few polite words often opens doors.
Talk to Your Local Pharmacy
Pharmacies are more useful as a contact point for a person whose health is in question in Europe than they are allowed by law to be in the US. If you are in a city and are closer to a pharmacy than an emergency room and your condition isn't critical, try the pharmacy. You might be surprised at what services a pharmacist can provide.
Take Advantage of Public Transportation
Public transport is much more extensive in Europe than in the U.S. You'll have a variety of ways to get from city to city, or even city to exceedingly small village. Where there are no trains, there will likely be buses, even if their schedules aren't ideal for the tourist. In Switzerland, Postal Buses will take you to just about anywhere you can think of going. For longer trips on trains, you'll want to find the right rail pass. If you're taking short trips or day trips, don't use a rail pass day, because rail passes aren't guaranteed to save you money, especially on short hauls.