Studentgoing:
I too am about to leave for Europe for a year. The main thing is not to have valuables hanging off you. No Nikon 35 mm cameras around your neck, no money wallets around your neck, no flashy jacket, shoes, etc. Be covert and you will be fine. I had a friend I met in Madrid who violated these guidelines and he got mugged. His fault! It is also why I dress like the locals, send my stuff in boxes and keep valuables in my carry on bag. Don't look like a victim. Most people are fine, but theives do exist. Use your gut feelings to not get into situations which you may regret later. For rooms I suggest Hostal Residencia Mondragon, Carrera San Jeronimo, 32, 5th floor. Wonderful family, clean cheap rooms, great guests and 2 blocks from the Prado and Puerta del Sol! Have a great time.