I agree with the above posts. Practice is key. I notice that many people are reluctant to do practice problems because of busy schedules, work, etc if the problems are not collected, but the reward will definitely be your exam scores.
Some other suggestions:
-Buy a solutions manual, if available. Many of them have detailed explanations on how to work out odd or even problems, but the concepts are very similar.
-Don't fall behind. I see students in the tutoring center who miss several sections then want to have it summarized in a one to two hour session and it just isn't feasible.
-Utilize your campus tutoring resources, if available. As mentioned, most schools have free tutoring services for G Chem, O Chem, Physics, etc.
-Visit office hours. They are very helpful if you can't seem to get a particular concept down and you have tried other resources.
-Understand the underlying concepts and use your reasoning abilities. Does this answer make sense?
Good luck 🙂
BTW, I hated chemistry in high school and recall probably doing mediocre at best in it.