Miscellaneous tips, from somebody who’s had a lot of long studenty summers to backpack in:
– Twenty days isn’t nearly as long as it sounds, especially when you factor in traveling times, and Europe is a lot bigger than it looks. So plan carefully, sit down with the train timetables and get a general sense of when and how you’re getting from place to place, and be prepared to cut out a city or two if necessary. It’s tempting to cram in too many places, but you should resist that temptation. (Honestly, I just got back from a twenty-day trip to Spain and Portugal, and it felt rushed.)
– For cheap food, keep an eye out for kebab shops, markets, and restaurants located in regular, residential neighborhoods or near universities. Avoid places located in the main tourist areas. Soft drinks are way expensive in Europe (I usually load up on tap water in the morning at the hostel, since water fountains are often scarce), but alcohol is usually a huge bargain, especially in Prague.
– If you go out in the evenings, for God’s sake don’t go to the Irish pub, you’ll just get way overpriced beer and stand around talking to the other English-speaking tourists. (Sorry. Am a bit grumpy about Irish pubs.)
– Set aside more money than you think you’ll need – it helps to have a slush fund to deal with all the incidental and emergency expenses.
– Have some laundry detergent, the powdered kind, on hand, but make sure it’s in a container that cannot possibly leak all over your backpack. (You may recognize the voice of experience talking here.)
– Walk everywhere you possibly can (except when you’ve got your big backpack with you). It’s free, and it’s an excellent way to experience a city.
– A few words of the language go a long way. Learn the phrases you’ll need most often as a tourist (“I’d like a ticket to…” “Do you have any vacancies?” “Where is…?” “Excuse me?” “Thank you,” etc.) and you’ll get major goodwill points, and spend a lot less time being confused. I’m amazed by the number of people who don’t bother to do this. (Amsterdam is an exception. Seriously, everybody speaks English there.)
– A few destination-specific things: Most of the good art in Rome is tucked away in churches, which are (yay!) free. I recommend having a look at the Rick Steves guide to the city, as it’s excellent at telling you where to find stuff. Make sure you eat well, and have lots of gelato, even if you need to splurge a bit.
The Vondelpark HI in Amsterdam is a really excellent hostel, but popular, so it’s worth reserving early. (Amsterdam, BTW, is gorgeous. Best experienced by walking around early in the morning, before the crowds hit.) Everybody goes to the Anne Frank house, but I recommend checking out the Dutch Resistance Museum as well if you’re interested in WWII history.
London: If you’ve got any interest in Shakespeare at all, try to see a play at the Globe, groundling-style. It’s cheap and great fun. Many of the museums are also free (in contrast to everything else, which is almost painfully expensive).
Hope you find some of this useful!