Hyphen use is relatively new to English punctuation. Although its origins aren't exactly clear, one could argue that its widespread acceptance came about as a direct result of the printing press. Printers needed a way to keep lines uniform, or even, and often ran into the problem of having to split, or separate, words that otherwise weren't separated.
One way to show where words were split was with the small dash we now call the hyphen; and thus, hyphen use was born.
Nowadays, the hyphen is used in a number of ways far removed from its humble beginnings at the end of a row of words on a printer's page. The hyphen is still used to separate words when there is no room for them at the end of a line but today, with computers and the 'forced justification' capacity, this particular hyphen use is rarely now seen.
How to use a Hyphen
Compound words are two or more words that are closely related and used together. Words like: free speech, jazz band and high school are considered compounds.
When compound words become commonly associated or so closely related that they form a new concept and are understood together, they morph, or evolve, into an hyphenated word. Words like: mass-market, anti-Americanism and pro-choice are examples of hyphenated words.
Over time, hyphenated words can lose their hyphen and become permanently joined. These types of words are then known as permanent compounds. Examples of permanent compounds are words like: makeup, supermarket, topsoil and minicomputer.
Now, if you are looking for hard and fast rules as to how and when to use the hyphen, then this is not the page to find them. However, the following is generally agreed upon with a few exceptions here and there. Check a dictionary or a good style reference if you still have any doubts about hyphen use. ;-)
ALL compounds use a hyphen: all-powerful, all-knowing, all-encompassing, etc.
HALF compounds use a hyphen: half-asleep, half-court, half-moon, half-wit etc.
SELF compounds use a hyphen: self-inflicted, self-control, self-righteous, etc.
SEMI compounds use a hyphen: semi-final, semi-skilled, semi-automatic, etc.
QUASI compounds use a hyphen: quasi-judicial, quasi-socialists, quasi-religious, etc.
Compound Adjectives with ILL, BEST, BETTER, LITTLE, LESSER, WELL, etc., take hyphens: little-known author, best-seller list, ill-fated journey, well-known fact, etc.
Adjectives ending in LIKE and FOLD can take a hyphen: ten-fold increase, coward-like retreat, etc.
What is the purpose of Hyphen Use?
There is plenty more that could be said about the hyphen, but I think the above is adequate for most instances.
Prefixes that may or may not require a hyphen are listed below.
pseudo-, under-, pro-, anti-, re-, un-, non-, semi-, co-, intra-, extra-, infra-, ultra-, sub-, super-, supra-, pre-, post-, over-, etc.
I hope the above helps you to make your writing more clear. One final rule to keep in mind is that unless your hyphen actually aids in clarifying your meaning or making it easier for your reader to understand what is written, then it's probably best, more often than not, to leave it out.