How do I write a good introduction?

The most important thing is clarity. At A level and GSCE, the examiner should know what you are arguing immediately; try summing up your argument in one succinct line. After that, it can be useful to outline the key points in your argument, alongside any key contextual details. The contextual detail should not be forced, but rather, woven into your argument. For A level history questions that ask which is the most important factor in causing an event, it is necessary to consider the factor given to you by the question, before stating why it is or is not more important than the other factors that you may have identified. For English comparative essays, it can be useful to outline one way in which the texts are similar in their treatment of a given theme, and one way in which they are slightly different. I have always been told that the introduction is in many ways the most important part of the essay. Writing a strong introduction both helps the examiner, and helps focus the essay by giving you something to refer back to when writing the rest of the essay.