Washington grew up lacking the gentlemen's education typically accustomed for the children of wealthy landowners. With few people to model his behavior on and an acute awareness of his lack of formal education, The Rules guided Washington's intentional actions, pronounced speech, civility to those of lower ranks, and respect for his superiors. Maxims like Rule 92, "Take no Salt or Bread with your Knife Greasy," and Rule 12, "Shake not the head, Feet, or Legs roll not the Eyes lift not one eyebrow high than the other wry not the mouth, and bedew no mans face with your Spittle, by approaching too near him when you Speak," indicated general actions to avoid in public.
Other rules delved further into professional and personal actions. For example, Rules 40 and 68 encouraged humility in interaction by stating, "Strive not with your Superiors in argument, but always Submit your Judgment to others with Modesty," and "Go not thither, where you know not, whether you Shall be Welcome or not. Give not Advice without being Asked and when desired to do it briefly."
Washington applied The Rules to various aspects of his life. During his military years, Washington expected a high level of decorum and cleanliness from his troops, referenced in Rule 51. He also promoted rules to his family, advising his stepgrandson, George Washington Parke Curtis that, "while a courteous behavior is due to all, select the most deserving only for your friendships," directly corresponding to Rule 56 which stated, "Associate yourself with Men of good Quality if you Esteem your own Reputation."
Washington's written Rules were originally published, along with various samples of Washington’s writings, in the mid-nineteenth century. They have and continue to appear in various newspapers across the country, and were first published in book form in 1888, with subsequent editions following. The widespread and continued publication of Washington's copy of The Rules has contributed greatly to the gentlemanly reputation that has helped define his image.
Source: Mount Vernon The Rules of Civility and Decent Behavior