I think for the essay, the prep books like PR and Kaplan
offer very good advice. I had a really general template and had some preconstructed sentences that had grammatical variety built in. Also, I was sure to use lot of transition words to signal various parts of my argument.
The week before the exam, I skimmed through all of the topics. I put a mark next to any topics I thought I'd have a really hard time answering. Then, I looked up some information on the topics on the web just to get an idea of what types of arguments I could use should I get those questions.
Luckily, on my exam I got easy essay questions... So, in other words hope for the best, but be prepared for the worst. Good Luck!