...begins with a definition and clear description of the subject; the lead section introduces and explains the subject and its significance clearly and accurately, without going into excess detail.
...is understandable; clear enough to be understood, yet goes into sufficient detail; thoroughly explores and explains the subject as to be comprehended by laymen and experts alike.
...is nearly self-contained; includes and explains all essential terminology required in the article, such that someone could completely understand the subject without having to read many other articles.
...branches out; contains wikilinks and sources to other articles and outside materials that may add new meaning or background to the subject or give relevant, connected information, so readers may easily understand where they should go for more background or information.
...acknowledges and explores all aspects of the subject; covers every encyclopedic angle of the subject.
...is completely neutral and unbiased; has a totally neutral point of view; presents competing views on any controversies logically and fairly, pointing out all sides without favoring any particular ideal or viewpoint. The most factual and accepted views are emphasized, and minority views given a somewhat lesser priority, while at the same time giving enough information and references for the reader to find out more about any particular view.
...is an appropriate length; article size is long enough to provide sufficient information, depth, and analysis on its subject, without including unnecessary detail or information that would be better suited for a child article ("subarticle") or related article.
...reflects expert knowledge; fact-based and rooted in sound scholarly and logical principles.
...is precise and explicit; free of vague generalities and half-truths that may stem from an imperfect grasp of the subject.
...is well-documented; reputable sources are cited, especially those which are the most accessible and up-to-date.
...is very clear; written to avoid ambiguity and misunderstanding. Begins with a definition, and follows a logical structure; uses clearly-worded sentences, grammar, and syntax.
...includes informative, relevant images, each with an explanatory caption. May include maps, portraits, photographs, or artwork; sufficient images to add to a reader's interest or understanding of the text, but few enough images that they do not distract from the article.
...is engaging; uses varied sentence lengths and patterns; language is descriptive and colorful while still maintaining encyclopedic tone.
...uses proper grammar, spelling, and writing conventions; follows all the accepted rules of modern English.
...cannot exist. By no means should you spend a lot of time worrying about how to make an article perfect. Perfection in general is an unachievable ideal. The joy of writing and editing is that perfection isn't required.