I learned that in order to get through the really crappy classes (Stat, Econ, Math) I had to take another that semester that I loved.
I second this. I only had one quarter in my entire undergraduate career where I didn't sign up for at least one "fun" class (other than music stuff), and one of my hardcore science classes ended up being the fun class (having a good professor really makes a difference...) Some of my fun classes included things like raptor biology (including a handling lab), tractor driving, archery, music theory, history of rock and roll... Some of these classes fulfilled major, minor or GE requirements, some didn't, but they were all for fun. My lightest quarter was 16 units ('full time' = 12 units), and usually I was taking 18-20.
While I never did badly in undergrad, I did learn a few things. University is not high school. I didn't have to study in high school to get virtually all As. In university, I spent the first year learning that I had to study (and go to class) and the next three years figuring out how to study. In high school, the "how to take notes and study" is sort of prescribed for you (some teachers required certain types of binders, and folders, and homework assignements, etc). In university, you go to class or don't as you want, you do the homework or not as you want, you take notes however you feel like, and you pass or fail based on how well you figure those things out. Yes, there's exceptions, but for the most part, everything but the tests and lab sessions were optional/suggested, and you figured it out from there. I borrowed study methods from most of my friends until I found the combination that worked for me. I am NOT a flashcard person. I learn best by hand-writing things over and over and over, and working through sample problems. Some people just have to reread their notes. Others record lectures and re-listen. Some people annotate the handouts or textbooks. Others type up summaries. It varies for everyone. It may take you a long time to figure out your method... I didn't truly figure it out til halfway through vet school (yes, this is after 4 years of undergrad, and into my 2nd year of a graduate program... I had a method that worked okay at the end of undergrad, but it took me another year and a half to more or less perfect it).
I also learned that having a study group is a good thing. My study groups in undergrad tended to meet a few days before an exam and independently work on homework problems or whatever was applicable to a particular class, and ask questions and get into discussions as needed. If we had enough people, at least one person in the group would actually understand every concept... and could make it make sense to pretty much the rest of the group. My vet school study group tended to meet the day or two before the exam and quiz each other on various concepts (which was useful because we all had different ideas of what was "important"). I never went to tutoring because I had smart people to study with, but it was definitely available, and some of my friends did take advantage of it. I rarely went to office hours for the same reason, but again, I had friends for whom it was a huge help.
The class I did the worst in was a chemistry class in which everything they covered I had already learned in high school. I didn't think I needed to study it because it was all familiar (and I therefore didn't go to class or do much of the reading and only perfunctorily worked through the problem sets). When I got the exam, I found out that while it was all familiar, I didn't know it as well as I thought I did.
As far as I know, most people experience a kind of study shock between high school and university. You're not alone. If your sorority requires you to maintain a certain GPA to stay in, then I hope they have some way of helping you out with that when times get tough. Most schools ought to have tutoring programs. Get together with your sorority sisters, dorm peoples, lab partner, whatever, and start to develop a network of people to help you figure out how YOU need to study.
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