Perhaps the most important detail in a business letter is keeping the format you use consistent and correct. Be sure to print your letter on good-quality paper or letterhead and to send it in a proper business envelope, one large enough to accommodate a page 8½ inches wide.

Use consistent margins and spacing. Generally, 1-inch margins all around work well, but you can use larger margins (up to 1½ inches) when your message is short. The top margin can also be adjusted if you want to balance the letter on the page, though the body need not be centered.

Finesse the greeting. Write to a particular person at a firm or institution. Address him or her as Mr. or Ms. — unless you actually know that a woman prefers Mrs. You may also address people by their full names: Dear Margaret Hitchens. When you don’t have a name, you might use a person’s title: Dear Admissions Director or Dear Hiring Manager. Or you can fall back on Dear Sir or Madam or To Whom It May Concern, though these forms of address (especially madam) are increasingly dated. When it doesn’t sound absurd, you can even address the institution or entity: Dear Exxon or Dear IRS — again, this is not a preferred form.

Distribute copies of your letter sensibly. Copy anyone involved in a message, as well as anyone who might have a legitimate interest in your action. For example, in filing a product complaint with a company, you may also want to send your letter to the state office of consumer affairs. Copies are noted and listed at the bottom of the letter, introduced by the abbreviation CC (for courtesy copy).

Spell everything right. Be scrupulous about the grammar and mechanics too — especially in a job-application letter. Until you get an interview, that piece of paper represents you to a potential client or employer. Would you hire someone who misspelled your company’s name or made noticeable errors? (help with common errors)

Photocopy the letter as a record. An important business letter needs a paper copy, even when you have an electronic version archived: The photocopied signature may mean something.

Don’t forget the promised enclosures. A résumé should routinely accompany a job-application letter.

Fold the letter correctly and send it in a suitable envelope. Business letters always go on 8½ × 11-inch paper and are sent in standard business envelopes, generally 4⅛ × 9½ inches. Fold the letter in three sections, trying to put the creases through white space in the letter so that the body of the message remains readable.