Really, you needed to start worrying about this earlier. Getting a high grade in any course is one of those self-reinforcing cycles. Improve your work a little bit early on and it iterates. Every bit makes every future bit that much easier. This isn’t inspirational-quote talk; this is just how it works. For mathematics courses, where most of the time one subject feeds into the next, this is obvious. It’s also obvious for mathematics-in-disguise courses like physics. But even for courses where one topic doesn’t directly lead to the next it’s so. Every subject has ways of thinking about its topics, the kinds of questions to ask and the typical sorts of answers they draw. The sooner you ask your instructor, your peers, and whatever tutoring centers are available — and they are — the better off you are.
That said, everyone wants numbers. So here’s my posts. This is the original, about how to calculate exactly the score you need on your final to get whatever course grade you want. It allows for different sorts of weighting and extra credit and all that. If you don’t want to worry about extra credit here are some tables for common final-exam weightings with which you can approximate your needed score.
Also: review the syllabus. Read and understand any study guides you have. Review the in-course exams and homework assignments. Eat regularly and sleep as fully as you can the week or so before the exam; you do not have any problems that sleep deprivation will make better.
(Yes, this post is early. The schools I’m loosely affiliated with started early this term.)