take cheapest flights available
Once you are here in Europe, with some sort of homebase, (for me, it's Norwich, UK) constantly look for cheap flights. You will find flights for under $50 all the time. sometimes, $20 if you are constantly looking. Be open to where you go, just buy the cheap flights. Then you worry about what hostel to stay at, etc. A great resource is Rome2Rio, it will help you find the cheapest flights and trains. You can also set it up to notify you when there are ridiculously low airfair. That is how we found £12 rountrip tickets to Madrid. I lagged like a week and they went up to 30, but still cheap AF. We found an amazing hostel in the middle of all the cool stuff for $15 a day and we booked an entire 8 bed room, there were 8 of us. If you can do this, it's so much fun! get a group of friends to agree to go somewhere and make everyone buy their tickets within a week ish... then get a big hostel room together. Party time! While at the hostel, they kept giving us free alcohol! There