"Do not overdo the literary device of hyphenating words that are not usually linked: the stringing-together-of-lots-and-lots-of-words-and-ideas tendency can be tiresome."
— The Economist Style Guide
There are some general guidelines which can help you determine whether or not words can, or should be, hyphenated and when they should not. Words with common or short prefixes generally do not require hyphenation. However, if closing up a word could cause confusion, a hyphen should be used. (An example would be recreate vs. re-create.) If you have a longer word where consonants are run together, these can be hyphenated for clarity. (One example would be cross-reference.) Whenever numbers are used to describe the age of a character, there should be a hyphen (for example, a sixteen-year-old girl).