First, academics.  People might be tired of hearing this, but it's 100% true: this is not like high school.  Unless you're in tiny classes— and the majority of introduction level classes have around two to three hundred kids in them— professors won't know your name.  That means have the option to skip lecture, to not do assignments, to not go to discussion and you won't have some adult obnoxiously harping on you.  However, that is the quickest way to fail out.  At the same time, if you're worried about the rigor, know this: if you go to classes, take notes, study, and start preparing for big assignments and exams a week before, you'll be fine.  Madison isn't about how smart you are, but the amount of work that you put into it.  That being said, try to avoid English 100, or the Comm Arts 100.  Those are the two, that I've heard of, that have a ridiculous amount of busy work that are only annoying.  I took CA 100 and was amazed at all the worthless, common sense stuff that was in the textbook.  Worst of all, with only 13 kids in a lecture that's taught by the TA, you have to go to every lecture.

Now, for the social aspect.  I remember being freaked out about the big campus, the drinking culture, and about which dorm I should be in.  First, while the campus seems ridiculously huge at first, it narrows itself down very easily.  One day of keeping your nose glued to a map, and you can get the just of the city.  Your dorm becomes its own community, as every one of them holds activities for freshmen so they can meet others.  You have classes that you may or may not make friends in— that's up to you.  Still feel too big?  Then take it in sections: make sure your classes are clumped together in one section of the city.  Next semester, keep them clustered, but see if you can pick a different part of town.  Get involved, whether its intramural sports or clubs, and you'll be meeting new people to hang out with everywhere.  Second, the drinking.  I believe the shakedown is about 70% of the University has admitted to drinking— which means that about 12,000 kids don't drink at all.  Whether you're into heavy partying, casual drinking, or staying in and watching movies, remember that there are thousands of kids who feel the same way.  You'll find a group that fits you.  And finally, the dorms.  I lived in Bradley, on Lakeshore, will be living in Smith in Southeast, and have friends in just about every dorm.  Here's what I can say about them: no matter which dorm you pick, you will find friends.  You will find people who want to do things, who want to explore the city just like you do.  The generalization is that Southeast is the party section, where there's always a drunk person, while Lakeshore is for the quiet, socially awkward kids who do not drink.  There will always be a party in Witte or Sellery, and it's always loud until at least one, from what I've heard.  Lakeshore has just as many people who drinks, but they keep it more manageable— not so much in the dorm, and not to the extent that Southeast does.  All in all, it's really up to you: if you want to meet a ton of people, but never be able to study in your dorm, do Southeast.  If you want to have a quieter dorm with a scenic view, though you have to walk a bit for the parties, do Lakeshore.  You cannot go wrong picking a dorm.