Buy every single one of her books (even if they are out of print) and devour them over and over. And make a point to read her Post column religiously.
Start with "Miss Manners' guide to excruciatingly correct behavior," out of print but widely available used. Do an Amazon search and you'll find quite a few good choices.
A thorough and careful reading, and continuous rereading, of Miss Manners writings will change your life and your approach to manners. She helps with not only the little details, but the broad picture, or what she calls "Heavy Etiquette Theory." She is thoroughly researched, practical, and always -- always -- correct.
Many people do not realize that good manners can be used as a weapon, both offensively and defensively. When reading her material, you will find she equips you with countless ways to "defend" yourself against other people's bad manners, by providing a glossary of responses that save you from becoming an unwitting victim of rude people, and giving you comebacks perfect for many occasions.
Although she can well-equip you to know when and how to use the most obscure items of silverware (like the chocolate muddler, the grape scissors, and the terrapin fork), what she really excels at is helping you really and truly understand what manners are, what they mean, and how to master their use in all circumstances. Yes, she gets a kick out of knowing (and telling you) that sable is the proper fur to wear in mourning, but she also tells you when funereal thank-you notes are required (for flowers, which are for the living) and when they are not (for mere visitations, which are for the dead, who cannot be expected to reciprocate).
Fortunately, she is also fun to read, extremely witty and entertaining, and always useful. And if she doesn't answer your questions in her books and columns, you can always write her (on white writing paper, in black or blue-black ink) care of the Washington Post.
Not being,
I am blessed to have two of the most well behaved children. Sometimes I'll sneak into my 14 year old son's bedroom and gently wake him by saying "son". He'll respond "ma'am" and I say "just checking" - he smiles and goes back to sleep. When my children spend the night out or attend a party, a parent will treat me with a phone call exclaiming what wonderful manners my children have. It is heaven. I, in turn, spoil them rotten.