It is time for a lesson in the finer points of etiquette. Miss Manners is sick to death of having to remind people to answer invitations, use surnames and titles in addressing people they hardly know, and to refrain from informing their wedding guests that their taste is for money.

She thought of staying out on the porch swing and refusing to budge until everyone had mastered the basics, but it's hot out and the iced tea is indoors. She has decided, instead, to pretend that everything is basically all right out there beyond the garden wall, and proceed to the more interesting details.

Here, then, are some more answers to questions that nobody asked:

* Ladies applaud differently from gentlemen. A gentleman smacks both of his hands together in front of him, but a lady holds her left hand straight out, palm up, and beats upon it with her right hand.

* Snuff is taken from a snuff box held in the left hand and placed with the right hand on the base of the left thumb, from which it is sniffed after the snuff box has been placed safely out of the way.

* In letters of complaint within an organization, the higher ranking person may "call attention to" a problem, but a lower ranking person should "invite attention" to such a matter.

* A duke has eight strawberry leaves on his coronet.

* The doggie bag is a Roman invention, guests at dinner parties having been given tidbits to take home with them. This lineage does not mean that the custom is always appropriate now, any more than are a few other Roman banquet customs Miss Manners could name.

* If your grandmother tells you she would rather have died than go out with her underwear in less than perfect order in case she got run over and was undressed in a hospital, ask her why those tiny enamel pins one sees in antiques stores are called lingerie pins.

* As the word "tuxedo" is considered vulgar by the fastidious, there is no correct way to refer to the sum of that outfit. One must name it by a part, as "black tie" or a "dinner jacket."

* Umbrellas should be rolled clockwise.

* Although it is rude to urge your guests to eat if they do not seem so inclined, watch out for anyone who takes no sustenance of any kind in your house. The Count of Monte Cristo was especially scrupulous about not eating the food of anyone for whom he had unpleasant plans. However, if you are under the roof of someone whose intentions you suspect, quick, eat and then hope he feels bound by the ancient Greek rule of not doing ill to a guest.

* On menu cards for formal, private dinners, the wines are not listed, although it is wise, if you are serving something special, to plant someone to ask the footman in a loud voice what it is. At formal public banquets, the wines are listed.

* Guests who are shown in by a servant are not considered to have officially arrived until they enter the drawing room and greet the hosts, which means that they get a free trip to the bathroom first.

* A former president of the United States is never correctly addressed as "Mr. President," although none of the current former presidents seem to know this.

All right, Miss Manners feels better now. Pretty soon she will have the strength to take up the cudgels and go around reminding brides to write their thank you letters.

Q.Our large and loving family consists of three generations, some in their sixth and seventh decades, some in their third and fourth decades and some ranging in age from a few months to five years. The first generation and most of the second generation object to little ones addressing their elders on a first name basis. Some second-generation family members do not object.

How does one solve this minor dilemma without causing resentment among the elders and total confusion among the tykes? What title is appropriate for a toddler to use in addressing a first cousin once removed who is an aunt or uncle to another toddler of the same age?

"Cousin Mary" and "Cousin John" are too archaic for any of us; "Miss Mary" and "Mr. John," widely used in the South, are not for relatives. Couldn't "Aunt Mary" and "Uncle John" be used by all the children until the age of reason?

A.Gather 'round, kiddies, and we will explain this system to you.

"Aunt Mary" isn't really your aunt Mary, dear; she's your cousin, but we didn't like the sound of that. Josie here is your cousin, you see, but you don't have to call her Cousin because she's the same age you are and doesn't mind just being called Josie. OK, she's not exactly the same age, but to us grown-ups, all of you are more or less the same age, even if she's 18 and you are 10.

Okay? Now, Uncle John is your grandmother's husband and Josie's father is your uncle, but he thinks "uncle" sounds too old--no, for him, not for Grandpa . . .

And so on. At this rate, these children are never going to reach the age of reason. Miss Manners maintains that each child is capable of learning the relationship to him or herself of each of the others and using the correct title or the first name alone, as that individual prefers.

Q.I have a friend who is constantly pointing out to me "all she does for me." Now, the truth of the matter is that I really do more for her than she does for me in a material way (simply because I have more material advantages than she does, not because of any effort or great sacrifice on my part). She constantly kids about how much I owe her and what a great sacrifice she is making to do some little thing.

I find this very disconcerting. It would be rude of me to say, "Oh, yeah, well, what about that and this and that, etc." Of course, it's a little rude of her to say what she says, but she has other saving graces. Furthermore, it's a kind of culturally learned thing. I notice a lot of people from her background carry on in a similar manner.

I would somehow like to point out to her gently that this is not endearing behavior. She does it to others, too.

A.Miss Manners is going to let your anthropological comments pass for the moment, but she suggests that you drop that line of thinking before you commit a much greater offense than that of which you accuse your friend. No one group has a corner on whining.

The way to deal with it is to refuse to accept it as kidding.

When she mentions the effort involved in doing something for you, make her stop doing it. "I wouldn't dream of letting you put yourself to that kind of trouble. No, no, no--I can easily find someone who really wouldn't mind." If she mentions the cost of something, whip out your wallet and start shoving money at her.

This should drive her crazy in short order. Then a humorless talk might be necessary. "You find this friendship very uneven, don't you? I'm sorry, I had always thought I was trying to do my share, but I guess you don't really feel there is mutuality."

There will be protests about your being "oversensitive"; ignore them. That is always the last resort of a rude person who knows she has been caught.

Q.My friend and I are having a combined party to celebrate our 14th birthdays. Most of the people invited will be friends of both of us. However, some of them will know only one of us.

How can we let them know that they're not expected to bring gifts for both of us?

Copyright (c) 1983, United Feature Syndicate Inc.