Many times in your writing career you will be asked to write to a specific set of guidelines. For newspapers and news releases that could be the AP style or for publishing the Chicago style. This might require you purchase a manual for writers. One very common manual is Kate Turabian's Manual for Writers of Term Papers, Theses, and Dissertations, which also covers the Chicago style. You can other manuals for writers at your local bookstore and library, besides all over the Internet.
Writer's Manual is a website that boasts of being 'the bragging zone for writers worldwide!' Their website is setup to promote fellow authors and freelance writers be detailing their successes in traditional/online publishing and freelancing. They offer to teach you the tricks of the trade and expose yourself to 'tried and true' methods of success. You can subscribe to their free newsletter and learn how to create a successful writing career. Their sister sites are: Writer Gazette (which was listed as Best Site by Writer's Digest in 2002, 2003 and 23005) and EbooksCafe, which is filled with a wide variety of quality fiction, non-fiction ebooks and POD books, and also providing authors with the opportunity to promote and sell books worldwide.
A book you Christian writers might be interested in the Christian Writer's Manual of Style. It is an essential tool not only for writers of religious materials but also for their editors, proofreaders, designers, copywriters, production managers, and even marketers. The Penguin Writer's Manual is a complete guide to every aspect of the art of writing. This is the perfect companion for anyone who wishes to express themselves elegantly and clearly.
The Philosophy Student Writer's Manual emphasizes writing before reading. It encourages critical thinking and it uses a reader-friendly approach and introduces the style of argumentative writing that is expected.
Manuals are written to ensure consistency and clarity in a publication. They aren't meant to hamper the writer's independence, initiative, or entrepreneurial spirit. Some of the most common style books and manuals are The Associated Press Stylebook, Strunk and White's Elements of Style, The New York Times Manual of Style and Usage, The Chicago Manual of Style and Wired Style from the editors of Wired magazine. These manuals don't apply to technical or academic writing although there are other sources to help you with that kind of specialized writing.