Look back over everything you got a grade on so far and check out what you missed - looking for patterns. If it is mixing up similar vocabulary words then you would change what you are doing in a different way than if you are having trouble applying broad concepts.
If you are making mostly stupid mistakes (getting things wrong that you really knew very well) then you fix it differently than if you have certain aspects that you totally don't get.
If you kinda sort know stuff for the quizes and homework so you get a lot wrong there but did well on the exams then you have a different fix than if you can do your quizes and homework easily without much looking things up but freeze during tests.
It depends on how your teacher grades: if tests are worth more, you should definitely aim to improve those scores! If participation and homework points are worth a big chunk, do all of the work and take every extra credit chance you get. I had like a 96 in my A&P I class, but the teacher graded iClicker questions and gave two extra credit projects that took FOREVER to do but were only worth like 5 points each (our class was graded out of 500 points, with the bulk being from the midterm and the final! ) In the end, those clicker points and extra 10 project points were enough to nudge me to an A+! It sucks, but it's worth it. Gotta do what you've gotta do, right?
Good luck! You can do it!