Abbreviations should be used sparingly in formal writing, but they do have their place. Here are some tips to use them properly.
Use abbreviations that your audience will know and understand. Do not make up your own version of abbreviations or abbreviate whenever you feel like it. Also, do not abbreviate a word simply because you think it is too long.
Refer to a standard writing style book for specific rules or questions. Any bookstore will carry a writing style guide that offers abbreviating help in MLA, APA, CMS, CE and other styles. Many online guides are also available. For example, if you need to abbreviate in AP style, an Internet search will produce several good sources.
Abbreviate titles. If you use a person's full name in writing, you are permitted to abbreviate their title. Mr. Edward Smith. Mrs. Regina Worthington. Samantha Jones, M.D. If you do not use their full name, you cannot abbreviate the title! For example, you must either say Professor Smith or Prof. John Smith. Another example: Representative Jones or Rep. Matthew Jones.
Utilize abbreviation when referring to people, organizations, countries and corporations. A good general rule is to think of FSS. If something is Familiar, Simple or Standard, you are safe to abbreviate it and not cause confusion with your audience. Some examples of safe abbreviations when writing: MLB (Major League Baseball), GOP (Grand Old Party, US Republican Party), NPO (Non-Profit Organization), NBC (National Broadcasting Company), USA (United States of America), JFK (John F. Kennedy) and GE (General Electric). Do not abbreviate an organization that only a small audience would recognize, like THCWFF (Texas Hill Country Wine & Food Festival).
Shorten your text by abbreviating dates and numbers. There are many accepted abbreviations for dates (B.C. meaning "Before Christ" or A.M. meaning "morning") and numbers (No. meaning "number" or $ for dollar amount). However, it is not acceptable to use an abbreviation as a substitution! For example, this sentence is not correct. "We went fishing in the A.M." The correct sentence would be, "We went fishing in the morning." Or, also correct: "We went fishing at 8 a.m."
Clarify, don't confuse. The purpose of abbreviation is to make writing more efficient and clear, not harder to read. Read your writing aloud. If your abbreviation makes the sentence foggier, don't use it.