Note: I graduated from MIT a few years ago, but I think not much has changed since then.
1.) Register for several classes (more than you plan to take), and then drop the ones you liked the least. I made it a practice of registering for 6 classes a term, trying them out, and then keep the 4 classes I liked the most.
Sometimes a class does not suit you, but can take time for you to figure that out. What I wanted to avoid is signing up for 4 classes, realize later on that I don’t like one or two of them, and be stuck with either having to take them, or dropping them and subsequently scrambling to try to add a class and play catch-up.
2.) Attend office-hours religiously.They are so helpful. When I first started out, I started to struggle with a few classes and my pride initially prevented me from asking for help. But office hours saved me. Case in point, when I took 6.042J, I got a D on my first quiz. I was livid. The material just was not making sense to me, no matter how much time I spent trying to study alone. But I started attending office hours and even got a tutor from HKN. I managed to finish the term with an A- in that class. Having professors and graduate TAs spend extra time helping you in a (typically) less populated setting, even personalized attention, was absolutely invaluable for me.
3.) I would suggest having no credit card. Students get bombarded by vendors with credit card offers, and I have seen some students go a little crazy once they have plastic of their own… cough cough myself included.
4.) When I came to MIT, I was wanting a single, and I ended up getting one at MacGregor. I regret that choice, as I am quite shy and would probably have been better off in a more open dorm setting where there are more opportunities for socialization. MacGregor’s entry layout did not lend itself to having a lot of foot traffic pass by my dorm room. I think I would have been better off someplace like Next House, where there could be more opportunity for people passing by and chances for social interaction. Granted, everyone is different, so you might be fine in a more private dorm setting. But for a wallflower like me, it was rather depressing.
5.) In so many ways. I was so used to being a big fish in a small pond back at my high school, that being at MIT surrounded by a lot of people who were way smarter than me was humbling, frustrating, and even embarrassing. I mentioned earlier that I initially struggled with some classes, and I was very disappointed in myself, got depressed, and was too embarrassed to show any sign of weakness and seek out help. But if you can get past that, you discover that MIT has a lot of resources available to help, from office hours to tutoring services to counselors. There is even things like the Sophomore Exploratory option you can do twice (which is awesome) and the Junior/Senior pass/fail options which again you can do twice.
6.) Best thing - being told by one of the 6.0.34 TAs that they discovered one of the exam’s solution sheet answers was incorrect due to what I had answered for that question, so they ended up making copies of my exam that I aced as a replacement solution sheet. That was really cool.
Worst thing - I remember walking past Officer Sean Collier many times on campus. He would sometimes be a cross walk guard in the morning or late afternoon. I would usually say “thank you” to him as I pass by him, while he paused traffic along Vassar Street, and he would always say “you’re welcome”. It still hurts, thinking about what happened to him.
7.) I knew I wanted to go into a math and computers science-related field, as I always loved those topics. I also knew that I wanted to pursue a PhD, so I tried taking a few graduate-level (H) courses that count towards my undergraduate major or electives.
I highly recommend Prof. Edelman’s Parallel Computing course, Prof, Demaine’s Geometric Folding Algorithms course, and Prof. Sipser’s Theory of Conputation course.