Studying abroad was the best decision I've ever made for a number of reasons. Most importantly, though, is the way you learn to be yourself - in more ways than just the traditional, first-day-of-school, "coming of age" film kind of way that we've gotten used to hearing about through mainstream media.
It's difficult to explain exactly what's going to happen during that first week or two that you're in a new country. It's a strange little bit of time; you haven't quite gotten into the rhythm of a new city, adjusted to the accents or the slang vocabulary, or felt the pang of homesickness that will inevitably come to you one day later on in the program.
The first two weeks of living somewhere is like being thrown into a swimming pool with your clothes on. It's funny and it feels a little odd, mostly because a part of your brain knows that something isn't right. You're going to find out that it isn't a fanny pack, it's a bum bag. You aren't alright, you're grand. When someone is feeling down or having a rough time, you say "aw, sugar," instead of "honey." Suddenly, everyone uses brown sugar in their coffee and macaroni and cheese is something you only see when your eyes are closed.
The best advice I can give you is to pay attention to the differences. If something doesn't make sense, ask about it. Stow it away to think about later, because by the time the third week rolls by, you're going to be doing all of those things, too. If you keep track of what's different, if you remember what it is that made it hard to get a handle on your new country, it's going to be a lot easier readjusting once you come back home.
Pay attention to them, but don't get stuck. That's what will bring you down. Think of how funny they are and bring up the differences with other people on the program; see what they've noticed that you might have missed.
Don't let the little things that don't quite jive weigh heavy on your homesick heart; instead, make a game of it. Try and pick up on what you can, and don't spend so much time trying to hold on to who you were and what you did before. Studying abroad is going to teach you how to be yourself without being held back by who other people know you to be; the best way to be okay with that is to forget who you knew you were before you left, because it's all going to be different once the trip is over.