Are you under the age of 26? Are you a student?
If you are a student, make sure you cash in on that fact!
Students get all kinds of amazing discounts all over the world from discounted train tickets, museum entry, hostels, city tourism cards, and even airfare (check out STA Travel for these tickets). If you are a student, always ask for a discount, especially in Europe, where almost everything is discounted for students. Don’t forget to also get an International Student Card (or if you are younger than 26, a youth card!).