Routledge's Manual of Etiquette

the long version

Compliance with, and deference to, the wishes of others is the finest breeding.When you cannot agree with the propositions advanced in general conversation, be silent. If pressed for your opinion, give it with modesty. Never defend your own views too warmly. When you find others remain unconvinced, drop the subject, or lead to some other topic.Look at those who address you.Never boast of your birth, your money, your grand friends, or anything that is yours. If you have travelled, do not introduce that information into your conversation at every opportunity. Any one can travel with money and leisure. The real distinction is to come home with enlarged views, improved tastes, and a mind free from prejudice.If you present a book to a friend, do not write his or her name in it, unless requested. You have no right to presume that it will be rendered any the more valuable for that addition; and you ought not to conclude beforehand that your gift will be accepted.Never undervalue the gift which you are yourself offering; you have no business to offer it if it is valueless. Neither say that you do not want it yourself, or that you should throw it away if it were not accepted, &c., &c. Such apologies would be insults if true, and mean nothing if false.No compliment that bears insincerity on the face of it is a compliment at all.