Organize your essay. Expository essays need to be in some kind of logical order. For example, if you are writing an essay about the American Revolution, organize each event chronologically. If you take a thematic approach, group each category together. Do not mention politics in one paragraph, military action in another and then jump back to politics again. This is sloppy and confusing to the reader.
Stay on topic. Never introduce unrelated information, even if it is connected with the subject. With the American Revolution as an example, do not spend several paragraphs on an extensive, in-depth biography about George Washington. The topic is not about his life, but rather his role in the subject at hand.
Provide sources for every statement. Unless you mention some common knowledge, do not write anything that you cannot support. Assumptions, opinions or observations do not belong in an expository essay.
Use credible sources. College professors will not accept vague sources, especially obscure websites. The best plan is to avoid the Internet altogether, with the exception of online academic journals. There is plenty of information in campus libraries.
Avoid plagiarism. Plagiarism can be intentional or accidental. Unfortunately, you can be penalized for accidental plagiarism. When paraphrasing, make sure the statement is in your own words. If you borrow even one sentence from a text, put the words in quotations and give proper attribution.
Leave out lengthy quotes. When you quote from a source, do not take an entire paragraph and paste it in your essay. Lengthy quotes are rarely necessary, clutter up your work with empty filler and indicate laziness. Large pieces of information need to be paraphrased.
Take your time. Never write an expository essay the night before it is due. Carelessness results in fallacies.
Edit your work carefully. One of the worst things you can do in an essay is include choppy sentences, poor grammar or spelling mistakes. You are trying to teach somebody about a subject. They will not take you seriously if your essay is shoddily written.
Be clear and concise. Convey your information as briefly as possible. Many students intentionally create wordy essays out of fear of falling short of the word requirement. However, a professor values content over length. The key here is quality over quantity.