Never break an engagement when one is made, whether of business or social nature. If you are compelled to do so, make an immediate apology either by note or in person.
Be punctual as to time, precise as to payment, honest and thoughtful in all your transactions, whether with rich or poor.
Never look over the shoulder of one who is reading, or intrude yourself into a conversation in which you are not invited or expected to take part.
Tell the truth at all times and in all places. It is better to have a reputation of truthfulness than one for wit, wisdom, or brilliancy.
Avoid making personal comments regarding a person's dress, manners, or habits. Be sure you are all right in these respects, and you will find you have quite enough to attend to.
Always be thoughtful regarding the comfort and pleasure of others. Give the best seat in your room to a lady, an aged person, or an invalid.
Ask no questions about the affairs of your friend unless he wants your advice. Then he will tell you all he desires to have you know.
A true lady or gentleman, one who is worthy of the name, will never disparage one of the other sex by word or deed.
Always remember that a book that has been loaned to you is not yours to loan to another.
Mention you wife or your husband with the greatest respect, even in your most familiar references.
If you have calls to make, see that you attend them punctually. Your friends may reasonably think you slight them when you fail to do so.
neat and careful in your dress, but take care not to overdress. The fop is almost as much of an abomination as the slovenly man.
If wine or liquors are used on your table or in your presence, never urge others to use them against their own inclinations.
-from "Correct Manners, a Complete Handbook of Etiquette"