Do you have your quizzes, midterms, etc? Most professors base the questions on the final on whatever they tested already. They'll be a good starting point if you can't get last year's test. Also, if he or she's nice guy, there will be more questions on what you've studied recently. Watch for the favorite reaction, nearly everyone's got a favorite and they'll test you on it for sure.
Finally, memorize those reactions! If it's an Orgo final, you'll be told to make just about everything from methane or benzene. In fact, you shouldn't be reading this, you should be reading flash cards with all your reactions and thier products on them.