Expository essays present an idea. Writers use details, evidence and analysis to investigate or explain that idea by comparing and contrasting facts, giving examples or explaining cause and effect. This type of essay typically starts by introducing its topic and pulling in the reader with an interesting statistic, a brief history of the topic or a thought-provoking question.
The purpose of the descriptive essay is to describe something, such as a person, emotion, object or experience. One way to begin a descriptive essay is to start with one detail. For example, if you're writing an essay about your mother, you might start by describing her eyes. The writer could also start the essay with one of the five senses; an intro focused on a garden, for instance, could begin by explaining the different scents of the garden's flowers.
Narrative essays tell a story, and they include all the classic elements of a story: setting, plot, characters, climax and conclusion. A narrative essay might begin with an anecdote or an introduction of a main character, or even a general statement, such as "Good friends are hard to find."
A persuasive or argumentative essay presents an issue and evidence for or against that issue. Persuasive essays usually begin by introducing a thesis statement -- one or two sentences that state the main idea of the paper. A thesis statement for a persuasive essay could be, "Limiting television results in better performance in school."
Reflective essays discuss the writer's growth during a specific period of time. Instructors sometimes ask students to write a reflective essay upon the completion of a class project or semester-long course. For this type of essay, an effective introduction would talk about the beginning of your experience. For example, a reflective essay about your summer would start at the beginning of the vacation.