The introduction is of particular importance to the reader as it sets out the approach that the rest of the essay will take, and is therefore instrumental in communicating the structure of the text. However, introductions are sometimes overlooked by writers, possibly because introductions can be difficult to write, or perhaps because the opening doesn't seem so important as the central points to be made in the main body.
It would be counterproductive to suggest a formula for a good introduction; apart from the natural variations in personal preference and the differing requirements of each individual essay, a formulaic approach can result in a somewhat clumsy introduction. Generic advice on essay structure often recommends that you: "say what you're going to say" (introduction), "say it" (main body), and "say that you've said it" (conclusion). There is some truth in this; however, the way in which you signpost your intentions can be done in a stylish or stilted manner. An introduction which simply started "In this essay I will..." might be an example of an overly simplistic approach. Instead of set phrases and ingredients, it might be useful to consider the reader's perspective.
Your reader has three essential questions when first encountering your essay:
You need not write your introduction first, but it is often helpful to consider your response to these three questions at the beginning of the process. There is no formula for a good introduction, and the responses to these questions could take a number of forms or appear in any order in your introduction, but the guidance in this section has suggestions to help you to develop effective introductions.
Supervisor's view:
"You need to establish the basis for an essay, but often a lot of time is wasted in introductions. This partly a matter of audience: there is no need to tell your likely readers the basic stuff that they already know. It's partly the risk of generalization: they often beg nasty questions. Often it's unnecessary summary of what will come later. Especially in exam essays, which are so short, I think often you don't need to say ‘in this essay I am going to...'."