As weird as this seems, it's true. People who were defensive when I edited in red ink protest less when the marks are in green. English has dozens of commonly confused words that the careful editor must check. Don't try to rewrite idioms to be correct grammatically. You'll only confuse yourself and the reader.
Idioms play by their own rules.
After you've checked all the facts, check them again. Remember, always, that style must help the reader. This applies to graphic design, word choice, punctuation, spelling, hyphenation, and anything else that affects the message. If it's against the rules but it helps communication, do it. If it follows all the rules but hinders communication, don't do it.