Style guides are rules for writing, and there are plenty of style guides around. The Chicago Manual of Style was created for newspapers and is used for many styles of publications these days. It's a good general style guide. Microsoft has its own style guide for technical manuals. One of the first style guides psychology and science students encounter is the Publication Manual of the American Psychological Association. (The sixth edition of this manual came out in July 2009, and it makes headings much easier than they were in the fifth edition.)
Creators of the APA style guide wanted to make it easier to read papers. Difficulty ensues when you read papers and they all have different formats and styles. How do you tell what the paper is about at first glance? Papers that adhere to the APA guidelines give readers, editors, and professors an easier time.
Some basics of the APA style include:
Fonts: Use Times New Roman for the content in your paper. Numerous studies have shown that serif fonts are easier to read than sans-serif. Serif fonts are the fonts that have little squiggles at the top and bottom of the letters. The titles and captions for charts and figures should be in a sans serif font, like Arial or Helevitica.
Your writing: Don't use 15 words if ten will suffice. Less is more. Make sure each paragraph is more than one sentence long and less than one page. Look for language bias and attempt to eliminate it. Remove jargon. Only use metaphors if necessary to explain a complex idea. Use active verbs. Less is more. Remove extra words. Indent the first letter of each paragraph. Double space the text.
Components of an APA manuscript: The manuscript needs to start with a title page and be followed by an abstract. The abstract gets its own page and should be less than 120 words. The text of the manuscript should starts on Page 3. Start the references on a separate page. Each appendix should start on a new page. The author note should start on its own page. A list of footnotes needs to start on its own page, as should a list of tables, and a list of figures.
Headings: Make sure you use the 6th edition of the APA style guide. The 6th edition has simplified heading rules, and the fifth edition has complicated rules.