1)I think many times people get poor grades because they develop a negative outlook on the material due to either their general perception of the material or lack of understanding the material when presented in class. For me, developing a positive attitude towards the material works. How? I read the material to be lectured the day before the class, and try to do some problems related to that section and KNOW the material prior to attending the class. I try to use the lecture as a review to re emphasize the material. This way, I don't get frustrated if I don't understand the material during lecture which can eventually cause you to have a negative outlook on the class and the material. This method has helped me get A+'s in most of my prereqs. Others may have different methods. But, for me the mental game and attitude play a huge impact on how I do in the class. So, I took actions accordingly to develop a positive attitude.
2) Ochem is very visual. If you can visualize things as much as you can, I think it may help since most people are visually oriented. If you can take a molecule (say a tetrahedral) and rotate it around at will, things like that will help with assigning R/S configurations, reaction mechanics (SN1 racemization, SN2 inversion) etc.....
3) If you can relate many things in ochem as a electrical phenomenon ie + and - attracting each other etc... the general concepts will come much easier. At least it does for me. Most of the behaviors in chemistry can be linked to how - vs -, + vs +, and - vs + react to each other ie nucleophilic/electrophilic rxns, VESPR theory etc...
I think the beauty of chemistry is that it may sound so esoteric, yet, it comes down to very basic ideas. Just my 2 cents.