1. Hyphenate nouns formed by the combination of two nouns standing in objective relation to each other, that is, one of whose components is derived from a transitive verb:

well-wisher wood-turning
mind-reader child-study
office-holder clay-modeling

When such compounds are in very common use, and especially when they have a specific or technical meaning, they are printed solid;

typewriter stockholder
proofreader copyholder
lawgiver dressmaker

2. Hyphenate a combination of a present participle with a noun when the meaning of the combination is different from that of the two words taken separately; boarding-house, sleeping-car, walking-stick.

3. Hyphenate a combination of a present participle with a preposition used absolutely (not governing the following noun); the putting-in or taking-out of a hyphen.

4. As a rule compounds of book, house, will, room, shop, and work should be printed solid when the prefixed noun has one syllable; should be hyphenated when it contains two; should be printed in two separate words when it contains three or more;

handbook, notebook, story-book, pocket-book, reference book.

clubhouse, storehouse, engine-house, power-house, business-house.

handmill, sawmill, water-mill, paper-mill, chocolate mill.