The punctuation error that seems to occur most often in the manuscripts crossing my desk is misuse of the comma. The Chicago Manual of Style (CMS or CMOS), The Associated Press Handbook, and most grammar books list different rules. Most publishers have their own style sheets, but they follow CMS, the standard in the book publishing industry. CMS is expensive so I suggest Strunk and White's The Elements of Style to help you with grammar, punctuation, and word usage. First copyrighted in 1935, that little 92-page book is packed with the basics.
Susan Titus Osborn is the director of the Christian Communicator Manuscript Critique Service. She has authored 30 books. You can reach her at email@example.com, http://www.Christiancommunicator.com/.