Organic Chemistry is often one of the rougher classes for a lot of people in college. I both took it and taught it, so I feel like I have a good understanding of what you should and shouldn't do. Here are 5 keys to success that I swear by:
1) Treat Organic Chemistry Like Calculus. I think one of the biggest problems I see with people studying for organic chemistry is that they treat it like a cell biology or biochemistry class. I think this is such a big problem because most people taking the organic chemistry sequence are biological science majors. When I took biochemistry, for example, I spent a lot of time reading the book, highlighting, making flash cards, and memorizing. This is a recipe for disaster in organic chemistry. I think people should approach studying for organic chemistry like doing a homework assignment for calculus. Nobody spends time reading the chapter multiple times and highlighting formulas in calculus without doing problems until a few nights before the test. In a math class, skimming the chapter is important, but real progress happens by doing problems! I'm not saying that reading the chapters is a waste of time. It's not. But if you don't supplement reading with doing the problems, you're doomed. As a rule of thumb, try to spend twice as much time doing problems as reading.
2) Master the First 5-6 Chapters. Everyone knows organic chemistry is hard. It's not a sneak-attack kind of course. But when you start, it doesn't seem that awful. If you did well in general chemistry, the first five or six chapters are kind of a repeat of general chemistry concepts like electronegativity, polarizability, Lewis structures, resonance, and acid/base chemistry. A ton of people see this and relax. This material needs to be mastered. You're going to have a really difficult time mastering aromatic substitution reactions in the second semester if you don't know how to draw resonance structures without much thought.
3) Always Use Your Model Kit! Organic chemistry happens in three dimensions. It can often be difficult to visualize a molecule from line drawings. An important part of success in organic chemistry is being able to judge the steric environment around a carbon. In every class I have ever heard of, you're allowed to use your model kit during tests. Always bring it. When you have to assign stereochemistry or draw chair conformations, it's a lot easier when you are allowed to cheat with your model kit!
4) Master Arrow-Pushing Rules. If you don't master arrow pushing at it's most basic level, you likely will dig yourself a hole you can't get out of. After the first test or so, a good third of the points on an exam will involve knowing how to do this. ALWAYS draw your arrows from electrons. So many people try to do otherwise, and those people will always lose all of the points. You won't have to deal with mechanisms on one test and then have them go away. They are with you for the whole class.
5) Stay Upbeat! This is Hard! Organic chemistry is hard. It's going to make you feel bad about yourself at times. Be prepared to meet the challenge. Many people take this class as sophomores and haven't really been pushed to the limit by a class before. They had an easy time in high school, and gen eds during freshman year. Just be ready for it and don't give up. Maintain good study habits and don't get behind.