If you are looking for a large website to book hotels or tours I recommend TripAdvisor. While it is not without fault I think the site gives you a good way to compare prices and also other traveller’s reviews.
As you probably know I am a massive advocate for train travel not only is it environmentally more sustainable its also a much more social way to travel. While there is a slow food movement travelling slowly is also a great idea.
I am adding links to Eurail and Interrail which you should consider particularly if you are a student or under 25 years of age. I travelled Europe on a 3 month Eurail card and it was GREAT.
If you normally live in Europe you need to buy an Interrail Card while if you normally live outside of Europe you need to buy a Eurail Card.
If you need a visa quickly or you are having trouble getting a visa for a certain country iVisa will help you.