Make sure it's grammatically correct and contains no spelling mistakes.
Give your article a title.
Break it up into short paragraphs with sub headers.
Use the most important keywords and key phrases as early in the article as possible, preferably in the first sentence, and at the very least in the first paragraph.
Do not overuse keywords or key phrases. Intersperse them naturally throughout the text in the natural reading rhythm of the article. The recommended keyword density is 1-3% .
Include the most important keywords and key phrases in the titles and sub headers.
If it makes sense in the text, put keywords and key phrases in italics, or bold them