Good luck all! Maybe tell us what exam you are doing and a quick report afterwards on how it went? Or other general comments to help you let off a bit of nervous energy.
Some quick tips for essay questions from me (I mark them!): stay calm and read the WHOLE paper first; make a quick plan for each question you'll be answering BEFORE starting to answer the first (this will bring out ideas and help prevent overlap); remember that two or three main points argued well is generally better than producing a "all I know about the topic" answer; show that you are able to THINK ABOUT the topic and make your argument/stance clear from the beginning and support it throughout - refer back to it too, a least in the conclusion but preferably in different ways throughout.
[ Will add more tips to post # 4 as we go along if we think of any good ones ]
More tips from others about revising, writing answers, how to remain calm, etc, etc?