Your Roommate: Some schools have online questionnaires for anyone living on campus who doesn't have someone in mind to live with. There are also schools that just pair you up with another random person. My first roommate freshman year was a a complete failure, and I'm sure I'm not the only one who had issues with their first roommate, because Woof and her roommate separated second semester too. I think among girls it's a little harder to imagine an immediate hatred for one another, like most college students are fearing. From what I've heard, and my limited experience, girls are a lot more easygoing than people give them credit for. As I said before, my first roommate was a failure. She and I didn't understand each other at all, she was into fashion and partying and I was into pokemon and MMORPGs. We never fought though, despite being so different, but when the room change period came up she decided to move across the hall with a friend of hers (which was GREAT, because I essentially had a single in a HUGE room). I think in most cases, this is the sort of situation you'll run into, where if you don't 'get' each other, you just don't have any real contact. She and I used to just say hi and bye to one another every day, and that's about it. I didn't hear much about serious roommate conflict, so I think it's pretty rare. Some schools, like mine, allow you to change roommates and rooms once a semester. Other schools, like Notre Dame, allow a roommate change once every academic year. Don't worry about what your school's policy is before you need to, but keep in mind that if you freak out at your roommate for little things, trying to get her to move out at the start of the semester to get a big single, you might be stuck with her for the whole academic school year.
Your Room: This is something I was incredibly worried about when I went to college, and it's something I can't really comfort incoming students about, because there's a huge variety of room sizes on my campus, as well as room types, and I imagine it's like that everywhere. I can only tell you what's on my campus, and there will most likely be something similar to what's on yours. Some of this will definitely help you out.
- Typical Double Dorm Room: This is pretty normal for freshmen, it's a room with 2 beds, 2 dressers, 2 closets or bureaus, and two desks with uncomfortable chairs. It can be really nice and big or it can be really tiny and unmanageable, it totally depends on the luck of the draw. I think big rooms are rare, but Woof and I have gotten them twice in a row now, so it's not impossible to be placed in them. They're typically next to the bathroom or at the end of the hall. I think there's a middle of the lane size, but I haven't actually seen it so I'm not entirely sure.
- Singles: If you're really worried about living on campus, and you have a lot of money to spend, then you could go with a single until you find someone you'd like to room with. A single is usually a little smaller than the smallest double, and includes a bed, a dresser, a closet or bureau, and a desk with an uncomfortable chair. It's not that much fum to live in singles, and I don't know many people who do it, but it would be an ok option for first semester freshmen if they're feeling a lot of anxiety about their roommates and they really do have the money to spend. I do not suggest living in a single your whole time at school, it doesn't really lend itself to socialization.
- Apartments: On my campus, there are two different kinds of apartments. There are the ones with the single rooms (ultra expensive) and the ones with the double rooms (less expensive). Both come with a kitchen, bathroom, and living room set up with appliances and a couch and chairs, maybe even a coffee table. They can be anywhere from 2 person to 6 person, and you'll want to check and double check whether or not the rooms are double, if you have a preference, because Woof and I learned the hard way that they aren't always up front about it. Also, sometimes freshmen can't move into the apartments, so you'll wanna check with your school.
- Townhouses: This is the one I know the least about. I believe that they can be single or double rooms, but they're most likely a lot like apartments. Freshmen are not allowed to live in a townhouse.
I plan on covering what you'll need for your dorm in detail later, but for now that's the information I have for living on campus. Definitely contact your school to see if they carry these options and if you can get there, they might show you a 'show room' in the building you're going to live in. It may be not as big or bigger than your actual room, so you should keep that in mind if you go.