Make sure you actually understand chemistry. It's not sufficient to just remember your notes. With organic, it's all about understanding how mechanisms work and not how well you can remember them. Ask yourself why things are happening: why is the curly arrow going from the double bond to the bromine atom during electrophilic addition? Why is the Cl- the leaving group rather than H- during nucleophilic substitution? etc...
A certain amount is also remembering standard answers to common questions, so you should also do as many past paper questions as possible.