I am a 25 yr old male from Aus and i am starting in Barcelona on May 31.
It's my first backpacking trip also. Dont worry about being alone, you will meet heaps of people!!
Italy (Tuscany) as suzan said sounds awesome, im doing majority of Europe as i have a few months to do it in.
One place you might enjoy is Poland (Kracow) i think thats how its spelt. Apparently its pretty cool place to visit,