I've never lived in a dorm with others, thank goodness, but I do have some experience on the teaching side of a college classroom. Here are a few no-brainers you should bring to school so your professors don't roast you.
1. A stapler. I know, I know. You're at school. These are all over the place. That doesn't change the fact that, one of these days, you're going to end up doing your homework at the last minute before hurrying off to class, and you may not have time to make pit stops. Know what your professor will be really unimpressed by? Barely-stuck-together pages of homework bound by folding the upper corner of the pages. Some of the meaner ones may be peeved enough to take off points. You don't want to lose points on the homework you took all that time to complete, do you?
2. Loose-leaf paper. Similar reasoning. Know what's even less impressive than homework that's not stapled together? Homework done on pages with little scraps of paper spanning one side where you ripped it out of your notebook. That doesn't look good to the teacher. It probably doesn't even look good to you. So don't do it.
If you want to lose lots of points for stupid reasons, try simultaneously ignoring the advice in both 1. and 2.
3. Self-restraint. If you're at a certain type of college, there will probably be a fair bit of partying. Often, you may be tempted to join in. I'm here to warn you not to get drunk out of your mind the night before an exam. Having a hangover tends to lower your score. Just saying.
4. Critical thinking. Unless your teacher is terrible, they have reasons for doing what they do. If they're following a specific algorithm to solve problems, understand why they're doing that. I say this since most of my experience comes from math-related subjects. You may have learned to just rely on finicky procedures, but following those without a bit of self-reflection won't always go so well. If you're doing a problem and end up with something like "8=13" for your final answer, you're bound to be doing something wrong. Fix that.