I also recommend practice questions. If you are assigned "odd" problems, do all the "even" as well. Buy a book of practice problems when you run out of the ones in the book. I personally reached out to a friend who had taken the professor I was planning to take and she gave me some amazing advice on what to expect from the course and the professor. As I know C's can make it difficult to get into a program, I would also recommend retaking the course. Just with your school first to see which grade they will consider or if an average of both will be taken.
Aside from doing practice, practice, practice...meet with your professor to review old exams. Start to try to find trends between where questions come from (lecture, powerpoints, textbook, etc.) and what goes is on the exam. Really try to figure out what you are or are not doing that can be changed so you see a better grade. Live in the professor's office hours, get a tutor, form a study group, and attend any SI (Supplemental Instruction) opportunities that arise. Explain each step of the problem out loud to yourself as you do it and try to stimulate as many senses as possible while studying (chew some minty gum while studying and the same gum while taking the exam). Check out Khan Academy, Crash Course, and other youtube channels with chemistry related help.
Hang in there! Chemistry is tough, but you can get through it.