Ninety percent of all spelling problems, the writing gods say, concern compound words. Should it be selfseeking or self-seeking? Is it taxpayer, tax-payer, or tax payer? In other words, is the compound closed, hyphenated, or open? Who knows? Not many of us. That’s why we all need a good dictionary such as Merriam Webster’s Collegiate Dictionary and The Chicago Manual of Style. I have made a long list of compound words that I’ve encountered often so I don’t have to keep pawing through these books. I have better things to do such as debating foreign policy with my cat, Mr. Cody. I swear he makes more sense than most of our presidents.
Be careful about how you tack the word like on to the end of words with more self-respect. Some combos are written as one word, including catlike and trancelike. Words using the suffix -like are generally closed unless they end with l or ll (sail-like, ball-like), contain three or more syllables (basilica-like), are compound words to begin with (vacuum-bottle-like), or are proper nouns or other words that are difficult to read when written as one word (Whitman-like). One exception, though, is Christlike.
Also beware of words that begin with co-. Such compounds are usually written as one word, as in coworker. Even after editing and proofing, go back through your text and double-check the compound words you’ve used, because spell check doesn’t catch all of them—or give you the correct way to write them if it does—and because the pain associated with compound words tends to make copyeditors hallucinate after about a hundred pages.
In addition—and I hope you know this already—do not hyphenate a term that combines an adverb ending with -ly with another word. For example, don’t hyphenate the word pair heavily guarded.