Compounds nouns like buildup, cleanup, and ongoing are not hyphenated. But when used as verbs, they are treated as two words: to build up, clean up.
Words ending in -like are usually closed except when they are formed from proper names or words ending in ll. (See Spelling section for the dictionaries to check.)
asphaltlike vs. Lougheed-like vs. drill-like
Compounds with self- and ex- are always hyphenated.
self-governing; self-conscious; ex-mayor
Do not hyphenate compass points when there are only two directions. Do hyphenate if there are three.
northwest
south-southeast
Hyphens generally do not follow prefixes—a few examples:
HOWEVER
Use a hyphen between a prefix ending in a vowel and a word beginning with the same vowel.
anti-intellectual; de-emphasize.
When alternative prefixes are presented with one word, the prefix standing alone takes a hyphen followed by a space.
over- and underused; macro- and microeconomic
Use a hyphen when the second element is capitalized.
intra-Alberta transport
Use a hyphen to distinguish between two meanings.
He resigned from the team vs. He re-signed with the team
Also: re-cover; re-creation, re-form; re-treat; un-ionized
Quasi is accepted as a standalone word and is only hyphenated when used in a compound adjective appearing before the noun.
a quasi-judicial organization but a quasi corporation