For the most part, I understand how to use the hypen.

1) Compond numbers from twenty-one to ninety-nine or such as in fractions one-third, three-quarters.

2) In prefixes like all-, ex-, quasi-, self-, and sometimes co-.

Examples: all-American athelete, ex-wife, quasi-professional, co-worker, and self-conscious.

3) In words beginning with a capital letter.

Example: pro-American, non-Protestant

4) To prevent two identical vowels or three identical consonants from meeting.

Example: Fall-like, semi-indecent

5) Can also be used to prevent confusion.

Example: recreation vs re-creation

6) My big problem comes in when it involves group modifiers. For some reason, my brain just wants to leave the group modifiers alone or link everything together in an endless chain.

Incorrect: His cough came from a two pack a day habit.
Correct: His cough came from a two-pack-a-day habit.
Incorrect: The burned out cars and broken windows are a result of the riot by pro-Quadafi supporters.
Correct: The burned-out cars and broken windows are a result of the riot by pro-Quadafi supporters.

Obviously, I’m still working on the last one:-)