Write an attention-grabbing first sentence, for example, giving a controversial or fascinating view of the novel, or author. Show a clear understanding of the essay title, but do not restate it. If, for example, you have been asked to discuss the world of Jane Austen, demonstrate that you are familiar with this time in history. Give a flavor of what is to come in the body of the essay, without going into detail on any of the points. Include your thesis in the last line of the introduction.
Assume the reader is familiar with the novel, author or piece of prose or poetry that you are writing about. Show clarity in your own analysis by having a good understanding of the subject before you begin to write. Think of the questions you want to answer in the body of the essay. Look several times at the way the question is set up, as this gives you a good idea of what is required.
Be confident in your writing, for example showing that you grasp the difference between descriptive and narrative styles, and between the theme of a novel or story, and its subject. Avoid meaningless statements that do not bring your points forward. Do not say what you are going to do, as in, "I am going to argue that..." Always read your introduction carefully at the end of the essay. This highlights any point you may have made in the introduction and not mentioned again.