A style manual provides the writing rules for this particular academic discipline. When you follow those rules, you can produce a work whose form is recognizable by other readers in the discipline. When all members of a discipline write professional articles in a common form, they can more easily understand one another. The style manual helps keep the members of a discipline in touch with one another.
Following the manual will cause you to present your paper in a consistent and readable form. Each manual will include information such as how wide your margins should be, how to present tables or illustrations, how to cite research within the text of the paper, what to document, how to abbreviate, and whether to write numbers as words or figures. The manual will explain how and when to make title pages and how to write headings within your paper. For example, if you have several sections in the main body of your paper, you may want to put a heading before each section. The style manual will tell you whether to capitalize that heading or whether to center it. When you use a style manual, your writing style will be consistent throughout your paper; it also will be understandable to the reader because your reader also will be a scholar who knows these standards.
Remember that your style manual fundamentally is used to locate rules about how to present the form and shape of your paper; however, some style manuals include sections about how to approach the subject matter of your research paper. Those sections often review how to select a topic, use the library, compile a bibliography, and take notes. Although these sections are not exhaustive, they may provide enough guidance for you to get started on your paper.
Usually, you will not use the manual to create the ideas in your paper; you will use it to determine form. Because you concern yourself with form after you generate content, you may not consult the style manual until you reach the final drafts of your paper. If you try to make your rough drafts conform to the style manual, you may slow down your creative process and interrupt your good thinking. If you are writing your first research paper and never have used a style manual before, wait until you reach the last stages of writing before you consult one for rules of form. At that point you will be ready to discover how to write headings, present numbers, create bibliographies, etc.
If, however, you are writing a thesis or a long research paper, you may want to consult the manual earlier so you do not have to rewrite parts of your paper. For example, if you consult the manual for bibliographic form, you can record your sources correctly as you go. When you finish your paper, you will not have to rewrite your bibliography (which can be several pages long) or go back to the library to search for bibliographic information you did not retrieve when you had the source. Graduate students will do themselves a favor by using a single style manual consistently throughout their graduate work so they can become familiar with the style requirements before the students begin their thesis work.
Choose a style manual according to your purpose. If you are writing an article for an academic journal, select the style used by that journal. If you are writing for a professor, ask her/his preference. Generally speaking, if you are writing behavioral, scientific, or social scientific research, use APA. If you are writing artistic or humanistic work, use MLA. Keep in mind that these are not the only two styles available; you may select the style that best fits your preferences and those of your reader.