Acronym rules

According to the Chicago Manual of Style, one of the most widely used writing and citation style guides in America, there are some basic rules about acronyms.

1) Spell it out on first use!
Unless an acronym is so well-known that spelling it out is silly and almost insulting (e.g. CD-ROM), you should spell it out upon first reference. Put the acronym in parentheses on first use, and starting the second reference on, just use the acronym. Take a look at the following example:

• The Association of Southeast Asian Nations (ASEAN) is an organization of 10 countries located in Southeast Asia. ASEAN was created in 1967 and aims at promoting economic growth and cooperation among its member nations: (o)
  
• ASEAN is an organization of 10 countries located in Southeast Asia. ASEAN was created in 1967 and aims at promoting economic growth and cooperation among its member nations (x): some readers may not know what ASEAN is. you should spell it out on first reference!
• The Association of Southeast Asian Nations is an organization of 10 countries located in Southeast Asia. The Association of Southeast Asian Nations was created in 1967 and aims at promoting economic growth and cooperation among its member nations (x): repetitive and wordy! use the acronym to make it succinct.

2) Lowercase vs. Uppercase
There is no reason to capitalize the first letters of a noun just because it has an acronym. You only uppercase first letters when the noun is a proper noun.

• Lowercase (non-proper nouns): free trade agreements (FTAs), improvised explosive device (IED), standard operation procedures (SOPs) ...
  
• Uppercase (proper nouns): American Bar Association (ABA), North Carolina (NC), Department of Defense (DOD) ...