To be completely honest i dont ever use hyphens in my writing. The number one reason for that is, i havent found a good reason for them. As i looked around i found a couple good rules of thumb.
1. Use a hyphen to join two or more words serving as a single adjective before a noun:

a one-way street
chocolate-covered peanuts
well-known author

However, when compound modifiers come after a noun, they are not hyphenated:

The peanuts were chocolate covered.
The author was well known.

2. Use a hyphen with compound numbers:

forty-six
sixty-three
Our much-loved teacher was sixty-three years old.

3. Use a hyphen to avoid confusion or an awkward combination of letters:

re-sign a petition (vs. resign from a job)
semi-independent (but semiconscious)
shell-like (but childlike)

4. Use a hyphen with the prefixes ex- (meaning former), self-, all-; with the suffix -elect; between a prefix and a capitalized word; and with figures or letters:

ex-husband
self-assured
mid-September
all-inclusive
mayor-elect
anti-American
T-shirt
pre-Civil War
mid-1980s

5. Use a hyphen to divide words at the end of a line if necessary, and make the break only between syllables:

pref-er-ence
sell-ing
in-di-vid-u-al-ist

For line breaks, divide already hyphenated words only at the hyphen:

mass-produced
self-conscious

For line breaks in words ending in -ing, if a single final consonant in the root word is doubled before the suffix, hyphenate between the consonants; otherwise, hyphenate at the suffix itself:

plan-ning
run-ning
driv-ing
call-ing

Never put the first or last letter of a word at the end or beginning of a line, and don't put two-letter suffixes at the beginning of a new line:

lovely (Do not separate to leave ly beginning a new line.)
eval-u-ate (Separate only on either side of the u; do not leave the initial e- at the end of a line.)