Find some hostels, I forget the name of where I stayed, but it was pretty cheap like 18 euro or something (about 20-21 US dollars)

Don't stay in Paris for one day, you won't get to see anything, probably too tired from the train/plane ride.

Any friends/family in europe, look them up and stay with them.

There's usually really cheap deals on airfare once you are in Europe, so you should look out for that, I think I saw in Germany an airplane ticket to the czech republic for 10 euro or something.

visit Budapest! Awesome city, and stay at the Station Guest House - party hostel very cool if you don't want to go to bed.

Romania is quite nice too, the train ride from budapest to sibiu is about 10 hrs. but cheap roundtrip ($40 though it might have changed by now) and romania is still not on the euro so 1 american dollar = 3 romanian Lei (and everything is priced pretty cheap as well).

always have important things on your person.