"Sensible" is probably the highest praise that can be given to a style guide. Neither a comprehensive documentation manual (such as the MLA or APA guides) nor a self-improvement book (along the lines of Strunk and White's The Elements of Style), a publisher's style guide should provide practical and consistent advice about matters ranging from abbreviations and preferred spellings to punctuation standards and acceptable terminology.
If you're not already committed to one particular code of conventions (such as The Associated Press Stylebook, "the journalist's bible"), consider befriending one of these free online style guides. Each has its eccentricities and limitations, and no two of them agree on every fine point of usage. But they're all sensible and reasonably consistent.
This list of online style guides was last updated on October 17, 2013. Note that the Yahoo! Style Guide (no longer available online) has been replaced by the Wikipedia: Manual of Style.
American Style Guides Online
- Garbl's Editorial Style Manual
Developed by editor and activist Gary B. Larson, this concise guide offers "writing and editing advice about abbreviations, addresses, capitalization, English grammar, numbers, organization terminology, plurals, possessives, punctuation, spelling, word usage, and the World Wide Web."
- National Geographic Style Manual
Online since 1995 and frequently updated by a team of editors, this is an alphabetically arranged guide to "preferred National Geographic Society style and usage."
- The Tameri Guide for Writers: Generalized Stylebook
Maintained by Susan D. Schnelbach and Christopher Scott Wyatt, the Tameri Stylebook is "based on the Associated Press Stylebook, which is the primary style guide for reporters and editors at daily newspapers and many periodicals."
- Wikipedia: Manual of Style
This style guide for all Wikipedia articles is intended to help editors "write articles with consistent, clear, and precise language, layout, and formatting."
Australian Style Guide Online
- ABC Radio National Style Guide
This glossary from the Australian Broadcasting Corporation "tries to pull many different writing styles together and provide rulings on spelling, punctuation and usage--niceties once hidden behind spoken delivery but now exposed in print."
British Style Guides Online
- The BBC News Styleguide (pdf)
Written by John Allen, a BBC reporter and editor for the past 40 years, this popular manual "is not a 'do and don't' list but a guide that invites you to explore some of the complexities of modern English usage."
- Economist.com Style Guide
John Grimond's online guide is based on the style book followed by journalists at The Economist magazine. The 10th revised edition of the hardback version of the guide was published in 2012.
- The Guardian, Observer and guardian.co.uk Style Guide
Edited by David Marsh and Amelia Hodsdon, this is the online version of Guardian Style. The third edition of this witty handbook was published in December 2010.
- Telegraph Style Book
Augmented by monthly "style notes" from associate editor Simon Heffer, this is the "official guide to house style" for The Daily Telegraph, The Sunday Telegraph, and Telegraph.co.uk.
Canadian Style Guide Online
- The Canadian Style
Compiled by the Canadian government's Translation Bureau, Canadian Style includes "useful advice for drafting letters, memos, reports, indexes and bibliographies" along with "concise answers to questions concerning written English in the Canadian context."