A few more thoughts on university life in general that might've helped me had I thought of them at the time:
I should've more actively dropped certain classes when it was clear from the first week that I was struggling: It may have been my fault, it may have been the prof's, or maybe it was just the combo that wasn't working, but blaming myself and trying to succeed by sheer act of will and determination was not a winning plan. Everyone sucks at something!
On the other hand, when class information just seemed to stick, and the As came without herculean effort, I shouldn't have been so quick to dismiss my success being due to the class being an easy "A": Maybe I had an aptitude for the subject and should have taken it more seriously.
A weakness of schools in general is that they can't teach you to be the person who employs all those brilliant, hardworking engineers and scientists! Some of the USA's most successful people seem to have realized this limitation, and gotten educated up to a point, then dropped out to pursue their vision. No one will remember Steve Jobs, Bill Gates, Mark Zuckerberg or Jack Dorsey for their college GPAs.