I came across this advice from the The Ladies’ Book of Etiquette and Manual of Politeness by Florence Hartley. I believe that both of these pieces of advice still stand today. Enjoy a little look back at Conversation Advice.
Never interrupt any one who is speaking. It is very Ill-bred. If you see that a person to whom you wish to speak is being addressed buy another person, never speak until she had heard and replied; until her conversation with that person is finished. No truly polite lady ever breaks in upon a conversation or interrupts another speaker.
It is a mark of ill-breeding to use French phrases or words, unless you are sure your companion is a French scholar, and even then, it is best to avoid them. Above all, do not use any foreign word or phrase, unless you have the language perfectly at your command. I heard a lady once use a Spanish quotation; she had mastered that one sentence alone; but a Cuban gentleman, delighted to meet an American who could converse with him in his own tongue, immediately addressed her in Spanish. Embarrassed and ashamed, she was obliged to confess that her knowledge of the language was confined to one quotation.
Best Vintage Memory Wishes,
The Lady Hooper-Brackett
The Lady Hooper-Brackett 