What is the perfect technique for reaching the top marks in the longer essay questions?

The key for a good 30 marker is sticking to the same tried and tested method. Start off by defining any key terms in your introduction and potentially referencing data you may have been given. Then in the heart of your essay you should be looking to make four points and then evaluating three of them, whilst using concise examples to illustrate your points. Make it easy for the marker by demonstrating a clear structure to your essay, if your separate points are paragraphed effectively then it makes it a lot easier for the marker to identify and reward them. Also, writing a brief conclusion can be a great way to get those key last evaluation marks.