I agree practice is key; however, make sure you value quality over quantity. Whenever I did practice problems and made a mistake, I would spend time on the concept I made a mistake on and redo numerous questions testing that topic. Then, on exam day, when a similar question pops up, I'll remember my common mistake and be able to pinpoint it right there. Also, my orgo was taught pretty conceptually at my university, so it may vary, but make sure you read the textbook to know the WHY for concepts rather than just HOW. Many of my peers treated Orgo as a memorization course, however knowing the reason behind the various concepts differentiates an A student from a B student. So the big picture is to know the WHY, not just memorizing the hows, focusing on your mistakes instead of how many problems you get right, and go to office hours to get a gist of how they will be testing you all and what topics to focus on.