How do I write a good introduction to an essay?

A good introduction is clear, concise, and shows the examiner that you have a firm grasp on the relevants concepts and material. I always start my introductions by setting out in a single sentence the main thrust of my argument. I find that this also helps me to be very clear in my head about what exactly I want to say in my essay and to stay focused on the important details. After having put forward your argument you can go into a bit more detail about the key themes that your essay will address and why they are relevant to the question. This should not be done in great depth however, as that will come later in the main body of your essay. Finally, the introduction is the place to question and clarify key terms that appear in the question. Examiners are generally looking for students to really engage with the specifics of the particular question that they have set and show awareness of the underlying assumptions.