Decide what countries or attractions you want to see. Europe is full of travel options, and unless you have tens of thousands of dollars and several months of vacation time, you will not see it all in one trip. Read different European guidebooks, such as "Best of Europe" by Rick Steeves or "The Rough Guide to First Time Europe" by Doug Lansky. Make a list of various places you would like to visit, such as the Eiffel Tower in Paris or the Spanish Steps in Rome. Try to pick a particular region as well; it is easier to visit clusters of countries that are close together as opposed to a handful of countries that are far apart. For example, you might visit England, Ireland, Scotland and Wales in one trip, or France, Spain and Italy.
Choose when to go on your trip. Base this on available time off from work or school, how much money you have versus how much time you need to finish saving and whether there are any time-specific events, such as festivals, that you absolutely must attend. In terms of how much money you will need, plan on spending around $1,000 on airfare, between $500 and $1,000 on a train pass (if you will travel by train) and about $100 to $200 per day (if you are staying in hostels or cheap hotels).
Summer is the most popular time to visit Europe, and also the most expensive. If you are looking to save money and avoid the crowds, go during winter. The weather will be cooler, and cold in some places. Determine how long you will go for, and an approximate date range.
Purchase your airfare. It is cheaper to fly to Europe round-trip (arrive and depart from the same city). Check airline websites, as well as discount sites like 1800flyeurope.com, europebyair.com or Europe.Kayak.com. Search for the best price and purchase your round-trip tickets. Be sure to purchase your tickets at least one month before your trip; purchase farther out in advance if possible to find the best rate.
Purchase a Eurail pass or make car rental reservations. If you are renting a car, obtain an International Driver's Permit at a AAA office. You will need both the International Driver's Permit and your regular driver's license to drive legally in Europe. Eurail passes are the most popular way to get around Europe. You can purchase individual train tickets or purchase an unlimited train pass in weekly or monthly intervals.
Make hotel or hostel reservations. Hostels are more popular among younger travelers, though you can stay at a hostel even if you are not a college backpacker. Hostels are a great way to save money on your trip, as most hostels cost between $20 and $40 a night, as opposed to hundreds of dollars per night for a nice hotel. Visit sites like hostelseurope.com and europeanhostels.com to see available hostels in the cities you are visiting and make reservations.
If you are staying in hotels, make reservations at any hotel just as you would in the U.S.
Make any reservations at attractions, restaurants or events that are required. Your guidebook or the attraction's website will indicate whether a reservation is required. Most museums throughout Europe do not require reservations. However, you can purchase tickets online in advance and avoid long ticketing lines when you arrive. Museums like The Louvre in Paris (louvre.fr) sell tickets online on their website, and on busy days, you can save hours by buying a ticket in advance.
Pack for your trip a few days before you leave. It is easiest to "backpack" through Europe, especially if you are by yourself or with a small group. This style of travel involves keeping all of your belongings in a backpack that you carry with you from city to city, as opposed to several suitcases. Plan accordingly: If you go during summer, expect warm days most of the time, but bring rain gear and some fall clothes as well in case it gets cool. Winter is cold in most places, so pack winter clothes if you are going during winter. Do not forget your passport, credit card, cash, camera and journal to document your trip. Bring any tickets or reservation numbers you have made as well. Finally, be sure to bring comfortable walking shoes, especially if you plan to do a lot of sightseeing and exploring.