The most important aspect of a quality explanatory article is clarity. If you describe a topic based on a definition or examples, take the time to draw out all the details so your audience can see the big picture. If you use cause and effect to explain your article topic, be sure that you connect all the logical dots and don't leave any gaps in your argument. Regardless of your method of exposition, aim for clear, concise sentences, and avoid ambiguous or poetic language.
Your whole article revolves around your thesis statement, so make it strong. Unless you are writing an article on a very specialized topic, your thesis should be broad enough to encompass a good amount of information, but not so narrow that it restricts your audience from understanding the material. When you formulate your thesis statement, keep in mind the length of your article. An article that attempts to explain the reasons for the outbreak of World War I in only two pages is not likely to be successful. Instead, focus your thesis statement on a particular aspect of the war or one specific country or person involved.
Unless you are writing an article on a very simple topic, you will probably need to gather textual support. Since an explanatory article doesn't usually express an opinion, stay away from biased sources and opt for objective information whenever possible. For example, if your article is about soil amendments, stay away from sources that are obviously biased either for or against inorganic or organic fertilizers, since their information may be less than objective. Interviews with qualified individuals are another way to obtain credible, objective information.
Like other types of articles and essays, an explanatory piece needs to flow easily from sentence to sentence and paragraph to paragraph. Since an explanatory article is meant to make an idea, process or object more understandable, it is especially important to utilize transitions to help your readers follow the argument or sequence of your article. Pay special attention to transitions between your body paragraphs. Make sure that they not only relate to each other, but that they are always in dialogue with your thesis statement.