Wait a minute—I think...yes, it's a hyphen!

I suspect the reason we all have problems figuring out where and when to use hyphens is because we use them so rarely. Their main use, of course, was to help typesetters keep the lines on a printed page nice a tidy by allowing them to put part of a word on one line and the rest on the next. As word processing programs matured, some of them took over the onerous chore of hyphenation. That would be lovely if it worked. It doesn’t. So, if you’re going to use the utility, be sure to go through when the task is done and check everything against the dictionary.

Then there are those adjectives. Is it level-headed or levelheaded? Do we go one on one or one-on-one? There’s no easy answer for this except “look it up.” The dictionary that comes with Word will often object to combining words that every other dictionary in the universe approves. If you’re working for yourself, pick one. If you’re working for a publisher, ask if they have a house style preference.

When should you use a hyphen with an adjective modified by an adverb? Is it well known or well-known?

As with many questions of punctuation in English, it comes down to whether the absence of the hyphen will confuse the reader. In the sentence “John was a first-class pilot,” for example, you need the hyphen because without it the meaning could be that John was the first in his class to become a pilot.

One thing I can tell you for certain. Never use a hyphen to combine an –ly adverb and a past participle used as an adjective: highly motivated, not highly-motivated.

Em-dashes and en-dashes are typographical characters--what word processors call “special characters.” They have very specific uses. However, the one that causes the most confusion is when to use an em-dash and when to use an ellipsis (. . .). This most often arises in dialogue.

If a sentence is interrupted, the proper punctuation is an em-dash. That applies whether the speaker is interrupted by someone else or cuts himself off. The latter can be a toughie--you’ll need to pay very close attention. The interruption has to be just that, not the character’s train of thought chugging off into speculation. The usual occurrences are when the character’s internal monologue is interrupted by some external event. In a manuscript, two hyphens are used to indicate an em-dash:


“But you said--”
“Never mind what I said. Do it now.”


In fiction, you also use an em-dash where in nonfiction you'd use a colon--to set off a clause or a list of elements that provides additional information about the main clause or explains it.

If, however, the sentence just trails off, or if the speaker is leaving an opening for a response, you use an ellipsis.


“I’d like to go, but…”


You also use an ellipsis to indicate hesitation:


“I know…I mean, I thought…Are you sure?”


Also use ellipses when showing one end of a telephone conversation:


“Hello?…No, Tom isn’t here…I don’t know…Well, if it’s that important leave your number and I’ll have him call you.”


The en-dash is rarely used in fiction, except to indicate stuttering:


“I–I don’t think you…should do that.”


Some places will use an ellipsis in that situation—again, either establish your own consistent style or find out if there’s a house style preference.

This is by no means definitive. Deciding how to use special characters requires having access to style manuals, which any aspiring editor or writer considering self-publishing needs to have. Whatever you do, don’t guess, because if you guess wrong you’re going to irritate the person who has to fix everything.