Hey !!
As scholarship chair for my chapter... I can say that you have already over come the most important factor that keeps most people's grades down... wanting to do something about it. You can have all the study advice ever... but if you just don't do it, your grades aren't going to improve. here are 10 tips that I am handing out to my chapter at my meeting on Monday.
1) Prepare and ask at least one question at every class, this of course means you must GO TO CLASS
2) At LEAST three times a semester visit your professor during office hours. Let them get to know you by face and name.
3) Sit in the first three rows of class
4) Review readings and the prior classes notes before class
5)Use the hours of 9am to 5 pm for school. If you have a job sometimes during these hours, take a look at your schedule and make sure to set aside blocks of time for studying. STICK TO THESE HOURS, don't let anyone bother you... and DO NOT GO OUT. Treat school work like a job.
6) Re-copy or re- read notes from each class later that day.
7) Start a study group in each of your classes of between 3 and five people.. get their contact info and meet once a month.
8)Post goals for each class on a desk, mirror, or in the notebook you take to that class so you see them all the time.
9) Use note cards to study instead of highlighting
10) ALWAYS do any offered extra credit.
As I said since you seem to want to improve... as long as you stick to it your grades will improve. GOOD LUCK