I agree with most of what EMTRN6785 said.
Med/Surg is the backbone of nursing. If you can't get the basics and knowledge of med/surg, then other areas of your nursing practice will suffer.
But you also have to realize it's tough and especially tough when you get hard professors, which was my case. I failed Med/Surg 1 the first time. I had alot going on personally and on top of that, I had a difficult professor. It really depends how your professor teaches, what kind of learner you are, etc.
Like what EMTRN6785 said, check out NCLEX books
, go through practice questions before a test coming up on the subject matter. Also, become good friends with your clinical instructor, since you see him/her and spend more time with him/her than the lecture professor, and if you have troubles he/she's more likely to know how you learn and help you.