I wish I'd been less afraid of difficult courses (took an intro anthro class instead of an upper division humanities class, because I was scared by the number of upperclassmen in it), because the difficult classes have been the most rewarding ones.
I wish I had taken second semester courses more seriously since my first semester was so simple that I didn't expect the sudden change in course load.
I also wish I hadn't been so terrified of office hours for the first few months.
Also wish I hadn't been so incredibly set in my major(s). Took on a double-major of something I've loved for years with something that I had only had one good class in during high school, and it's taken me a year to drop that awful second major to take on a minor that I love with all my heart.
And I wish I had figured out the school/city bus system faster.