Hyphens with Compound Modifiers

Hyphens join words together. Use them to form a single idea from two
or more words.

For my money, the AP Stylebook has a clearer explanation in its
"Punctuation" section than Working With Words. If confused, try AP.

Here are some guidelines to common problem areas:

If two (or more) words are used to modify a single noun and come before that noun in the sentence, you hyphenate them.
Examples: the family-owned business; the out-of-state student; the pueblo-style building

Note that articles ("a," "an" and "the") generally are not hyphenated unless they're in the middle of a phrase.
No: A-first-rate movie
Yes: A once-in-a-lifetime opportunity

If the modifying words come AFTER the noun in the sentence, you usually don't hyphenate them.
Example: The student, who lives out of state, went home.

But this rule has at least two exceptions.

* Compound adjectives beginning with "well" are hyphenated no matter where they are in the sentence.
Example: The dog, which seemed well-behaved, sat quietly.

* When a modifier that would be hyphenated before a noun comes after a form of the verb "to be," you usually keep the hyphen to avoid confusion.
Example: The business was family-owned.

Do not hyphenate adverbs that end in "-ly." (So you need to recognize whether the "-ly" word is an adverb. These words generally are NOT adverbs: family, friendly, manly, timely.)
Examples: an easily remembered rule; a friendly-looking wildebeest

If two normally hyphenated modifiers apply to the same word but are separated by a conjunction or a preposition, you probably have encountered the much-feared SUSPENSIVE HYPHENATION monster.

* The modifier closest to the noun is hyphenated normally.

* The other part of the modifier gets a dangling hyphen, so the reader can see the connection.

* The connecting words (for instance, "and" or "to") are not hyphenated.

Examples: the 3- and 4-year-olds; a 10- to 15-year sentence; energy- and cost-efficient design