Couple more things:
About attending: You should attend class for all the reasons people said above, like getting the professor to know you, but ALSO because for YOU to get to know the professor. Especially in classes in the sciences there are always more topics than can be tested on test day, so if you attend class and know your professor, you tend to pick up on what he or she thinks is important in a topic. A.k.a. you start figuring out material that will be focused on for the exam. Its like cheating without actually cheating, lol. But its also a good exercise, my freshman bio prof was known to throw in some tricky wording and flip flop ideas in your head, so my study group would go over notes and try to come up with crazy flip flops and double negatives and junk (he actually didn't use double negatives, but its just an exercise). Turns out...three of the crazy Q's we made up were prettty darn close to three Q's on the final. It was my first perfect test, it was amazing!
Teach other students: Mastering concepts is being able to take an idea, and being able to make new examples/different ways to look at it AND still be absolutely right. It means your critically thinking, and its fun if you get a good one. Sometimes you realize you have know idea what your doing on a topic, and can actually learn it yourself. Your study buddies love you too.
Picking a study group: I only did this for a few classes, and it was really more for moral support at odd hours of the night, but if you choose a group of friends to study, make sure they are not leeching off of you. I mean that, some friends are simply lazy, great people! but lazy... Having friends who don't get things as fast as you is not a bad thing, because they actually want to learn and are trying, and some day they might be better at a class than you. They will no doubt return the favor.
Time Management = Organized from Eyes open to eyes closed:
Simply stated, for most good applicants for med school, 24hours is never enough. Anyone have a dream where suddenly the solar system changed and we gained an hour everyday, 25hrs! I can cure cancer! Or, you gained a super power of never having to sleep, WOW. Anyway...Med applicant has to juggle much more than just classes. Research, volunteering, clubs/org, and Friends <---Good to not become socially inept.
This means managing your time like a beast. Studying shouldn't just be about learning material as weird as that sounds. Studying also has to be efficient. The ratio is more important because as it allows you to use the time saved to do more in 24hours. Thats why, I use this trick:
Plan studying by content per day, and NOT studying time per day.
Figure out in advance how much material will be in a class for the next exam. Evenly distribute the material (to best of your knowledge at the time), over the period of time before T-day. Give yourself days where your doing other work, so this can be on the back burner, but get the content fixed on days. Hit your goals for content without looking at TIME! The point of this is that instead of using time as benchmark for how much you've studied, you use content. This forces you to be efficient, because if you spend 5hours on a chapter because you spend 3hours on facebook, that sucks for you, cause you still have 2 more chapters you planned to do that night. You learn your lesson, quickly. You have to look at those 3 hours on facebook as the time you could of spent relaxing, its gone now so say goodbye... By committing yourself to a schedule you gain endurance as a student, and its rewarding to get it done.
WARNING: You tend to get over ambitious some days, and set unreachable goals, by experience you gain how much you can really accomplish. Its good for learning about where your abilities are, and tracking your improvement as a student.
Time saving: Travel time! The hours of your life moving from place to place. Shrink it, with a commuter bike, packing food in the morning or night before, planning your errands. This is more micromanage, but I was getting close to 2 extra hours a day from just packing meals and eating on the go, and planning errands to shorten walking time. Never got a commuter cause my campus sucks for bike thieves, but I regret that now.
Lastly about notes. That is completely based on the class. Some classes require you to draw graphs and pics, not happening for most on the computer. I used multiple ways to study because it makes everyday a little different even if your actually doing the same thing. Making things are good learning, but time consuming. Usually a last resort.