[BeetleB]

I'll add a crazy one:

Don't go to an undergrad program where they inundate you with lots and lots of homework.

I went to an "average" university for my undergrad and a top one for my grad. Once I got to the top one, I was shocked at how much the workload was for undergrads (but not for grad students). The undergrad homeworks and exams were mostly grunt work - not the type of homework that makes you think deeply about the material (fortunately, the grad courses gave you that type of HW).

As such, students spent most of their free time solving problems that did not give them much insight.

My average undergrad didn't give insightful homework either, but the HW wasn't that demanding so it freed up the time to ponder over the material, etc.