You might want to bid on Sloan courses for first term, that is before you arrive on-campus. There are instructions on the Sloan Bid site that will help you navigate the process.
Bidding for spring courses happens in early December, so you want to try choosing electives early. The bidding process should be fully explained via notes before the Thanksgiving holiday. If you want to bid and don’t hear anything by then check in with the SDM office. The hard part about choosing electives at this point is that you don’t know enough to do the thorough job you’d like to do. Don’t panic! Bidding can close some classes to you, but there are plenty that do not fill and other ways to get in.
Bidding becomes your “pre-registration,” status, and it gets updated on Registration Day (day before first day of classes, see MIT Academic Calendar on the web). You can also add/drop courses during the first week of classes easily. After that, there are time limits and more signatures are needed. The first week of classes is treated as a “shopping period” by students across MIT, so changes are expected.
Get to know whoever is on campus from the classes ahead of you, they will have very useful information, and will be in your “second year” classes. Especially any 17-monthers (what 13-monthers often become after the first 5 months) who are finishing up that which you are attempting.)
For full-time on campus students, you can safely take four courses in Summer. Doing so will not make the Summer much fun, but it will make the Fall much easier. Given four courses in the Summer you should aim to take either five or six courses in the Spring, and either three or two courses in the Fall. If you are self-sponsored then try hard to do six in the Spring as you will need that extra time in the Fall for job-hunting. Do not try to take more than six ‘credit’ classes a semester unless you want a nervous breakdown.
Early on (mid-January) decide where you are going to work. You have many choices: in the SDM student area (crowded, noisy), in the libraries (too quiet), in your home/dorm (too many distractions), or perhaps in your RA/TA location, or in one of the many lounges and study areas on campus. Then organize yourself to work at that location efficiently and effectively – make sure you have a desk, a place for your books, your files, and access to a telephone and printer.
Be aware that there will be different amounts of 'visiting' students each semester - one semester the Residence Inn may be the focal point and the next semester folk may all have flats in Harvard – and so don’t be fooled by where everyone is in January.