My tips for getting good grades are pretty simple.
I came up with my own little method.
1. You become who you hang out with. If you notice in college theres always a group of people who ends up dropping certain courses. The other people in that group tend to drop too, because they studied together. I really truly believe you are most influenced by the people that surround you. The people that make A's in the class, Study with them or study on your own and ask them questions. Reasoning behind this is, if you have a question on a certain topic, you can always ask your friend to explain it to you in 5 mins. Whereas if you have to look it up in the book, read the whole section over it and than comprehend it on your own. You get much more efficient studying if you bounce questions off each other.
2. Old tests. Old tests help so much, it helps you grasp concepts and also lets you know what kind of questions your professors like to do. Some professors even put a small number of there old questions on your test and the more pool of old tests you have the better in the scenario. Old tests are great. I find that I learn reversibly from old tests sometimes, like when you come across a question you don't know, you look it up and you end up reading over the whole section on that subject, so when the teacher makes up new questions on the same subject, you are prepared to answer.
3. Know which professor to take for which coarse. If you go to a big school, there usually are multiple teachers for one coarse. Use rate my professor or pick a prof to see which teachers are better or which teacher you have a better chance getting an A in. If you have friends who have taken that coarse you can ask for tips in doing well in that class. Talk to your professor alot, about what you need to know to prepare for tests and this helps later on when you ask them for LORs because they remember you.
This is my 2 cents.... I didn't do exactly outstandingly well in undergrad, but I practically did this and it worked for me and got me to where I want to go. I had alot of my own free time, which makes me believe that this is the most efficient way of getting through school. I know alot of people who would study alot more than me in certain coarses and I would still come out on top with studying less than half. Smart Friends, Old Tests, and Good Professors.