All I have are cliche stuff (that has personally worked for me):
Just keep your nose to the grindstone and don't give up. Don't be discouraged by your failures, we all fail...repeatedly. Take it as a chance to learn something new, cuz you never know when it'll be useful. One thing our youth affords us, is the chance to constantly screw up and learn from it; let's take advantage of that while we can.
Don't worry about memorizing facts all the time; just understand the basic concept and you can reason things out for yourself later. Make sure you give yourself plenty of rest; "play-time" is just as much of an investment in yourself as work. If you don't rest your heart will go resentful and your mind and body will grow weary.
Ah... what else...
Oh ya, don't be afraid to google, hit message boards, ask questions and read books. Admit to yourself that you don't know something, and seek the answers out; don't try to get by, pretending to know something just so you can finish studying quicker or impress your colleagues. Sometimes you just need to take a breath, and re-read that chapter over again, and ask questions. There's nothing wrong with that.
Try to vary your sources; I always try to buy at least 2 books on the same subject, by different authors. I try to get one book that offers a simplified explanation, and one that goes in-depth. Again, google is your friend. Y'never know what u can find online.
Being a "b-student" means jack-diddly in the real world. School is mostly about memorizing facts. The real world is more about problem solving; so the quicker you can think, and the more creative you are in your field, the better off you'll be. So don't worry about your grades too much, as long as you're confident in your capabilities, and aren't afraid to learn new things on the job, you'll do great.
I'm only 24, so I'm still trying to figure things out. So far I'm also finding out that having good social skills can go a long way; so go out there and network (IRL), make new friends and always keep your ears open to opportunity. Start now, so by the time you graduate you'll have contacts in industries and can easily find jobs etc. knowing the right people can pay off big-time.