Get your backpack before you go. This may be the most important decision you make on your trip. A good backpack will make your life easy, while a bad one will have you cursing throughout your journey. Get a backpack that is legal to carry on an international flight. This is usually 9 x 14 x 22 inches or 22 x 35 x 55 cm. The total dimensions should be no more than 45 linear inches or 112 linear cm. These are easy to find since travel backpacks are made to be carried on airplanes. The best travel backpacks are convertible. There are zippered compartments that allow you to hide the backpack straps and make the bag look like an ordinary luggage. Be sure your backpack has a handle and wheels. This is a must. It may be called a backpack but you will be rolling it most of the time when it gets heavy.
Pack light. Everything you take to Europe must fit in your backpack and a day pack. You will not be checking luggage because you must carry everything you bring. Take two days' worth of clothes plus a long-sleeved shirt and light jacket. Do laundry in a sink every night or two. No one will care that you are wearing the same thing all the time. If something wears out, buy a replacement in Europe. Toiletries should be in travel sizes. You can always buy more. Leave room for your camera, journal and travel book. Traveling light is essential to enjoying your trip.
Take as much time as you can. To truly appreciate backpacking through Europe, you need more than one month to wander. It is even better if you can arrange two or three months. Calculate what you will spend on airfare and train travel, then add $50 to $100 per day depending on how expensive you want your food and lodging to be. Travel as long as your budget allows.
Buy a Eurail Pass before you go. A Eurail Pass allows you unlimited travel on European trains for a specified length of time in a specified class of service. You can also tailor the Eurail Pass to specific countries. A Eurail Youth Pass offers unlimited second-class service to travelers under 26 years old at a discount. The second-class service is just like first class, except it can be a little more crowded at times. Backpacking around Europe has always been about train travel. It allows you time to absorb the culture of a country and opportunities to meet locals and other travelers. Discount air travel may rival train travel in cost, but it fundamentally sacrifices the very essence of the backpacking experience. Stick to the train.
Get cheap airfare. If you plan ahead, you can get amazing deals to Europe. London tends to be an inexpensive entry point. Just understand that the United Kingdom is not included on the Eurail Pass so you will have to pay extra to get to the European mainland. Wherever you decide to fly into, be sure you purchase a round-trip airfare. "Open jaws" airfares into one city and out of another tend to be more expensive.
Make sure your passport is up to date. It should be valid for at least six months after you plan to return home. If you don't have a passport, start applying to get one at least three months before your departure date. Visas are not required for Americans traveling to most of Europe. If you are a citizen of another country, check the embassies of all the countries you plan to visit for visa requirements.
Take a good budget travel book. There are many book series that appeal to backpackers in Europe. Most notable are "Let's Go," "Lonely Planet" and "Rick Steves." They offer great tips on food, lodging and sights. Once you are in Europe, ask fellow backpackers for recommendations. Travelers often have much more updated information than books.
Convert your money on arrival. Thanks to ATM machines, it is easy to get local cash. Be sure you have a four-digit pin number. Many European ATM machines only take four digits. Also, be aware of any fees your bank charges on foreign ATM transactions. You can use credit cards in Europe, but you will be charged a bigger fee. Traveler's checks are another option, but they aren't used much anymore. You pay to get the traveler's checks, and then pay again when you convert them into local currency. ATM cards are the best option for cash.
Enjoy the backpacker's lifestyle. Go wherever you want. Do whatever you want to do. Ride on trains, stay in hostels, eat food standing up in markets. Live cheaply and have rich experiences. Force yourself to meet and interact with strangers even if you are traveling with someone. Keep a detailed journal and take lots of pictures. If you buy something heavy, mail it home. You need to travel light to enjoy the backpacker experience. Always be willing to head in a new direction if something appeals to you. The only appointment you have to make is your flight back home.