I had that shit down to a science.
First Year: Depending on the class, I'd attend roughly 60-90% of the time. GPA high 3.
Second Year: Pretty much the same until the end of the second semester where I utilized all sort of excuses during a bus strike and service strike at the school to basically stop attending for the last month or so. Didn't do well on one exam which seemed to focus on material pretty much covered solely in that last month but GPA remained in the 3s.
Third Year: This was the initial cause of some academic problem, mass confusion in the registrars office and a pretty big blight on my academic record. I worked roughly 30 hours a week, had a few deaths in the family, and one of my best friends at home died. All during the onset of my first semester of this year. I was flying all over the place, missing a lot of school and this pretty much set the tone for the rest of the year. That year I may have attended 5-10% of classes. Generally, I'd get the outline, find out when shit was due and when the midterms were and attend those classes. I dropped a lot of classes that had heavy workloads so I wouldn't have to go to actual lectures/labs. I missed a couple of midterms and had one semester with a retarded low average. I partied a lot and I'm still of the opinion it was totally worth it. This was about the time I started playing a lot of video games and found my way over to that first site we had after The Grey King invited me. This year led to a contested 'required to withdrawl' which may or may not still be on my transcripts (I contested it, won, and it should have been removed. Last time I actually checked, which was years ago, it was still there so I fired off a letter. I haven't checked again but it hasn't come up, so I'm not too worried about it).
Fourth Year: This is the year I got really good at not going to school. Maybe attended 25% of my classes. I had a class with a friend where I attended one lecture that wasn't a test or an assignment hand in. I got over 80% in the class and the friend remarked that if I had attended 2 classes I'd probably have somewhere around 160%. This is where I discovered that classes with online notes are key, actually opening your text books is a good idea, and you can pay people in bottles of vodka or rye for a copy of their entire lecture note set right before midterms or exams. Also, if you go out of your way to talk to most professors and offer to make up for missed time they cut you a lot of slack. I rocked out of this with nothing impressive, but probably an average around 2.8.
I think I could have kept on the fourth year route, but really at that point I wasn't learning anything at all and needed a pretty big break from school. It all worked out I guess.