Disclaimer to put in front of any reference work:

• Notice: General and comprehensive books such as this one necessarily leave out some things.

Reminder for any book that presumes to tell you what to do:

• "Nothing is at last sacred but the sanctity of your own mind. (Ralph Waldo Emerson)"

Tool to soften the tone of any know-it-all (written by hand by the reader at the end of the article or book)

• ...I guess