Though there are many Btown-related things to discuss, I'm going to start with what I thought was most important as an incoming freshman: classes. I distinctly remember getting my class guide the summer before my freshman year, sitting down on my couch and reading the entire thing front to back, all whilst marking it up with sharpies using a fairly intricate key.
I was an exploratory major, so I felt that the options were limitless, and I have exercised that impression every semester since then when I've chosen my classes. I've actually gained a reputation among my friends for taking whatever interests me the most without much regard for turning it into a coherent degree. I would argue, however, that it all worked out because I have two majors and three minors, the most of anyone I know, plus I took other fun classes that didn't even count toward those. So my advice to you, future college student, would be to take what interests you because that's the most effective strategy toward figuring out what you want to major in and ultimately what you want to do after graduation.
To highlight this strategy, I'll give you a play-by-play of what I took that first semester in Bloomington:
Introduction to Scientific SCUBA. I had always wanted to get certified in SCUBA but had never had the opportunity, primarily because Indiana is located nowhere near an ocean. But that apparently didn't deter the people in the HPER school from making a class out of scuba diving. Half-lecture, half "lab" (swimming through hoops and diving for things at the bottom of a pool once a week), I highly recommend this class because it truly shows how you wondrous a college course can be.
Spanish 312. I'm pretty sure the Spanish department has rearranged their course numbers since I was a freshman, but if you are an aspiring language student, I will try to emphasize this as much as possible: the AP test IS helpful and DOES matter. Spanish was the only AP class I got a 5 in and it definitely contributed to my graduating on time and taking culture classes that are infinitely more fun and interesting than the grammar and linguistics classes, as necessary as those might be.
Sister Species: The Chimpanzee. All College of Arts and Sciences majors (I'm not sure how this applies to the other schools within IU) have to take a Topics class. I recommend getting this out of the way your freshman year because remembering three different requirements you've put off until your second semester senior year to take can definitely cramp your style. This particular course is one of the most random I've ever heard of, but it was interesting enough and I could tell you quite a bit about our sister species, the chimpanzee.
Introduction to Psychology. This was the accelerated version of this course, since it combined two semesters into one. If you took psych in high school, and liked it, definitely take this one because it opens the door to a lot of other interesting classes in the department, and easily allows you to grasp two semesters' worth of material in a far more economic three months.
Religions of the East. I was especially excited for this class because I was ready to broaden my horizons and learn about cultures previously unknown to me. It was originally intended to be a one-off religions course, but I liked the professor and structure so much that I continued taking classes in the department and ended up majoring in Religious Studies. It was pretty much a complete accident, but it shows that taking what you're interested in can lead to unexpected things.
So this was a pretty specific overview of my first semester as a freshman, but the overall message is to take what you want to learn about, and you'll eventually be able to find what you want to get your degree in.