Refer to “The Associated Press Stylebook” and use the following guidelines when you abbreviate:

addresses Spell out roadhighwaycircledriveterrace and all similar words on all references. Use Ave., Blvd. and St. only with numbered addresses, but spell out if no number is included.
Right:1400 Orange St.
Right: The party is on Ivy Street.
Wrong: 1400 Orange Street
Wrong: The party is on Ivy St.
Abbreviate compass points only with numbered addresses.
Right: 1400 E. Orange St.
Wrong: The store is on E. Orange St. 

and, ampersand Spell out and; do not use unless it is part the official name.
Right: Barnes & Noble
Wrong: Waddell & Bleske were both there.

Christmas Spell out Christmas, do not use Xmas.

Days Spell out all days of the week on all references.

Measurements Spell out all measurements: inchesfeetpounds, etc.

Months Abbreviate months with more than five letters when used with a date.
Right: Sept. 5
Right:The conference is in August.
Wrong: September 5
Wrong: The conference is on August 5. 

Organizations Abbreviate only well-known groups and organizations on first reference:GOPYMCAFBICIA. Always double check the abbreviation in “The Associated Press Stylebook.” Do NOT use parentheses to explain an abbreviation on first reference Describe lesser known organiza tions instead of abbreviating. First reference: Committee to Prevent Nuclear War; Second reference: the committee, or the anti-nuclear war group. Right: The Federal Aviation Administration investigated the crash.
Wrong: The Federal Aviation Administration (FAA) (Cont.) investigated the crash.

Percent Spell out percent, do not use %.

States Spell out state names when used alone. Abbreviate when state has six or more letters and is used with a city. Spell out AlaskaHawaiiIdahoIowaMaineOhioTexas, and Utah always. Double check abbreviation and see city names in The Associated Press Stylebook for exceptions.
Right: Smith lived in Nevada for one year.
Right: Smith lived in Reno, Nev., for one year.
Wrong: Smith lived in Nev. for one year.
Wrong: Smith lived in Reno, Nevada for one year. 

Titles Refer to AP on all titles. Abbreviate military and police titles when used with a full name. Do not abbreviate president, vice president, mayor, superintendent, principal and professor.
Right: Capt. Jesse James
Right: Captain James
Wrong:  Captain Jesse James
Wrong: Capt. James 

United States Abbreviate United States with periods.
Right: The U.S. is a large nation. 

Miscellaneous Spell out fort and mount when part of a name.