THE CHRISTENING, for newborn Christian babies, is one of only two social events that most people have in a lifetime in which they can be both the undisputed center of attention and completely free from the responsibility for either the arrangements or their own behavior. The other such event comes for us all at the extreme other end of life. Brides of any faith or lack of it make a serious mistake if they attempt to treat the wedding as an occasion for stardom untempered by duty and preparation; nobody ever said it was easy to be a women.

At any rate, the baby who is having a christening may cry and yell, turn purple in the face or drop off to sleep in the middle of the festivities -- actions we have all be tempted to perform at other social events, but mustn't -- without being disgraced.

The burden of behaving thus falls on the parents, the godparents and the guests.

What the parents must do, in additionto producing the baby, is to:

Arrange with a clergyman the appropriate time and place for the ceremony. A church christening usually takes place during the church's off hours. A home christening, if permitted, requires that a formal table be set up with a bowl, usually silver, to be used as a font.

Send out informal invitations -- that is, individual letters giving the time, place and baby's name and a sentence of urging, such as "We hope you will be able to join us", or the information may be written on the parents' card -- to relatives and close friends. This is not an occasion for the casual acquaintance.

Give a small party afterwards, such as a luncheon or tea party. Cudle, a hot eggnog punch, and white caked iced with the baby's initials or other such fancies are traditional, but most people prefer champagne now to a heavy glug.

Decorate the house in flowers and the baby in white. When the baby wears the traditional elongated christening dress, the whole thing takes on the charming look of a postscript to wedding.

Choose the godparents, from among their extremely close friends, whose general outlook of life they would not object the baby's sharing.

The godpaent's duties are to:

Hold the baby at christening.

Present it with a present of some permance, such as one of the many adorable silver objects of unknown usage on which names and dates can be engraved.

Act as second-string parents to the child, providing moral and religious instruction, birthday and Christmas presents and asylum when the child has had a teen-age quarrel with his parents.

The duties of guests are to:

Put on dressy clothes (no black for women) and attend the ceremony and party.

Declare convincingly that the baby, though alternatively dozing noisily and yelling itself purple, is perfectly beautiful. MISS MANNERS RESPONDS

Q. Just how necessary is it to return an invitation? Periodically, when my husband and I are invited to dinner at the house of a work colleague or a casual acquaintance, we spend a dull, uninteresting evening. The atmosphere is friendly, but the group just doesn't hit it off and conversation lags. Are we absolutely obliged to invite our hosts at these gatherings to our house for dinner -- and face another ho-hum evening?

A. And then they'll ask you back, and you'll feel obligated to ask them back and -- don't you see years of dreadful evenings ahead of you? Of course you do. That's why you asked the question. And perhaps your hosts do, too.

Somebody has to call a halt to this nonsense. Most of us hardly have time these days to see people we already like, let alone people we might come to like, let alone people we don't take to and who probably also find us dull.

Miss Manners trusts that you wrote these people immediatly after their dinner, thanking them for a lovely time. Unless you are known far and wide for the number of parties you give, leave it at that. They will never know if if you realize how ill-suited you are to another, or if you are just among the increasing number of people who find they don't have as much time as they used to for entertaining, and who keep meaning to get around to giving the perfect little dinner one of these days.

Q. I am tired of being treated like a child. My father says it's because I am a child -- I am 12 1/2 years old -- but it still isn't fair. If I go into a store to buy something, nobody pays any attention to me, or if they do, it's to say, "Leave that alone," or "Don't touch that," when I haven't done anything. My money is as good as anybody's but because I am younger, they feel they can be mean to me. It happens to me at home, too. My mother's friend who comes over and doesn't have any children of her own doesn't know what's what, likes to say to me, "Shouldn't you be in bed by now, dear?" when she doesn't even know what my bedtime is supposed to be. Is there any way I can make these people stop?

A. Growing up is the best revenge.

Q. Having recently moved to a new apartment, I find myself in an awkward position and need your ever-so-wise and tactful advice. My new landlord is very friendly and at times quite flirtatious. I find him interesting and attractive. The delicate nature of a landlord-tenant relationship must call for a unique approach, for while I wouldn't mind having my rent lowered, I wouldn't want to end up on the street.

A. Miss Manners rarely has occasion, these days, to warn susceptible young ladies about the evils that will ensue from accepting not-disinterested generosity of men. But surely you are an innocent young thing if you imagine for one moment that any amount of animal passion will motivate a landlord to lower the rent. It is much more likely that, bursting with love, it will occure to him to move in with you can continue charging you rent. the consequenses, should the romance not work out, are more dire even than you imagine. Suppose it is you who decide, after you know him better, that you do not wish to continue seeing him, although he is still enthusiastic about you. There he will be, nevertheless. He is an excellent position to observe whom else you are seeing, which is the worst position one's former beau can occupy. He proably also has a passkey.

Therefore, Miss Manners cannot in good conscience recommend a tenant-landlord romance. If you find him irresistable, she recommends giving him notice. About your apartment, that is. If he does not then offer to put his own roof over your head, you can still leave a forwarding addres.

Q. One of the things I do for a living is give lectures. I don't get rich on it, but I give audience their money's worth, and I have worked up some good speeches that people seem to enjoy.

Word gets around, of course, and I am often asked by small groups, such as clubs and professional organizations, to give luncheon speeches or answer questions at their meetings. But often, when I accept, I find that they have no intention of paying me!

Perhaps I should bring it up when they invite me, but I assume that they know I am a professional, and it seems crass to demand payment while they are telling me how wonderful they've heard I am, how much everyone is looking forward to hearing me, and so on. These same people wouldn't dream of offering me for free the services or goods they sell, of course.

A. Nor would these people be embarrased to put price tags on their goods or send out bills for their services. All you have to say is, "What is your budget for speakers?" or "Why I'd love to; do you know my fee?" Remember that selling one's time is not necessarily a shameful transaction, depending on what one spends that time performing.