My first trip to Italy was also my first trip out of my home country. It was totaly worth all the money and effort that went into it. I went with my school on a two week study abroad tour. We Began in Venice, then hit Florence (my favorite) and then on to Rome with a few day trips to Assisi and Pisa.
When in Florence, if at all possible take a climb to the top of the “Duomo” (the Basilica di Santa Maria di Fiori). The view from the top of the cupola is worth the clostrophobic and physicaly chalenging climb of what seems like a million stairs.
Also, dont over pack. There are PLEANTY of shoping opportunities everywhere you go… and I ended up buying an extra suitcase to put all the stuff I couldnt pass up into.
Italians as a general rule are super friendly and happy to help you get to where you want to know. Try to beat the crowds when visiting the super turisty sights by getting there really early before they open or about two hours before closing. – And PLEASE PLEASE dont think you have to get to all the “sights”. Take time to enjoy passing through the market, or wandering around a part of the city where the locals hang out. And make sure you try the gellato.