Next: Which ones should
Normal people take three courses a quarter during their beginning years.
Masochists take four. As in all social settings, there are outliers that
extend beyond this range, but it is not recommended that you be one. If
lots of courses seem fascinating (a feeling that fades after the first year
or so), consider just sitting in on some. You can do this in just about
any course. Of course, you don't learn as much as when you do a course
properly, but then you don't sweat as much either.