This can be a hassle if you leave it to the last moment. Plan ahead of time; once you are accepted to the program, try and get a flight scheduled. StudentUniverse.com is a great place to start looking.
This is extremely important. Do a trial run first (pack everything you think you will need). Then take out things you can buy over there (some things are very expensive over there… like American food (so if you can't live without peanut butter... bring some) but NUTELLLA IS AWESOME!!!! Look at your airline size/weight charts to make sure that you are not over the weight limit. But what you should focus on is the size and weight charts for your connecting flight! You don't want to be throwing away clothes or paying 100 more Euros to get your bag back home.
Check the weather before you leave. In the spring semester it will be cold!!!! Warm weather shows up around mid April. In the fall semester it is warm for maximum of the first month and a half then its gets really cold. Your packing should reflect the weather.
You will be living in an apartment. It will be fully furnished meaning towels, sheets, a comforter, a pillow, pots, pans, and silverware are provided (so that means do not bring them with you; more space in your luggage). Dryers are not always provided (so just assume you will not get one). Love your kitchen because it will save you money (if anything goes wrong you can call your landlord).
You get around Florence by walking. You can get around Italy with trains. You will get familiar with the train station because you will be using this religiously to get in and out of Florence. The airlines that are really cheap to get around Europe are EasyJet and RyanAir. Try not to use taxis because they are very expensive.
You will be buying your own food so the central market is a great way to find fresh ingredients. Also CONAD is an inexpensive grocery store that is a really great place to go to if you are on a budget. CO-OP is more like the Costco experience and you need to take the local metro to get there. Also don't forget the staples Gelato and Pizza!
You will be buying your textbooks when you are there, so do not worry about that. You have to take Italian (101 or a more advanced one depending on how well you know the language). There is extra tutoring sessions you can use to your advantage if you get stuck with the language. A cooking class would be a great addition to your schedule because the Italian cuisine is spectacular and you should make an effort to know more about it.
Now this is important when you first arrive in Florence because you are just getting used to the city. Also it is nice to know that you have someone with you when you are exploring.
I know that sometimes when in another country many people want to buy everything they see because it will remind them of their trip to Florence. Taking pictures is a great alternative for that. Buying a lot of material things is spending a lot of Euros and using a lot of space in your luggage! I am not saying don't buy anything; just don't go crazy with the purchases you are there for three and a half months!
You are in Florence!!! You are going to have so much fun. Everyday should be an adventure. Also try and either keep a journal or Blog! This is wonderful for the future when you return and want to remember all your experiences.