There are few elements of punctuation that cause as much dispute among Copy Editors as when to “properly” use a hyphen. Sometimes, it seems like if you ask three different people, you’ll get three different answers. For example, we all know that hyphens connect modifying words, but sometimes it is unclear when the terms modify each other.
For the complete hyphenation rules, see the Chicago Manual of Style. For absolute accuracy, consult the latest edition of Webster’s Collegiate Dictionary. Do your best, but don’t worry overmuch about one or two misused hyphens; in the grand scheme of things, as long as the reader can understand what is being stated in the sentence, the information presented has served its purpose.