At the end of 4 quarters of university, my gpa was just above 2.0. My SATs were really good, so this was a disappointment. I just didn't know how to study. At the end of that quarter, I changed my major to something I was really interested in (that helped!), and equally importantly, began doing the following:
a) I quit cutting class. This is VERY important.
b) I started taking notes. When the prof emphasized something, I would WRITE IT DOWN. This forced me to pay attention and try to understand the flow of the lecture. Some people say that taking notes is an elaborate way of not paying attention. Baloney. It also gave me a WRITTEN RECORD of each lecture. This is also very important.
c) Before each test, I would go over my notes. I would go over them about 5 or 6 times. The first time was slow. It would take maybe 30 minutes. The second time it would take about half as long. The third time, half of that. By the sixth time, I would fly through several weeks' notes in a minute or two. This has the added benefit of being able to add repetitions in very brief odd moments before the test.
d) I would take the test, and be astonished to just walk through 95% of the material in an amazingly short time. I'm a fast test taker anyway, and this would cut the time down to almost embarrassingly short--sometimes I would sit around for several minutes just to make it look good. Seriously!
I graduated with a 3.4 gpa, despite the extremely slow start and the fact that I'm in serious competition for laziest person on the planet. 3.4 might not sound like much in these days of grade inflation, but in 1971 (yes, they had universities then) it was a respectable gpa.
I guarantee that just about any literate person can use the above method and get a B average. Reading the textbook is optional, but recommended if you want A's. Student life is a lark when you've got the system wired like this. It basically spoiled me for everything else I encountered afterward.