BOOKS OF THE TIMES

SELF-HELP. By Lorrie Moore. 163 pages. Alfred A. Knopf. $13.95.

''DO you believe in God?'' a character in one of Lorrie Moore's stories asks. ''We have a mutual agreement,'' her friend replies. ''I won't believe in him and he won't believe in me. That way no one gets hurt.'' To avoid getting hurt - that is what all the characters in ''Self- Help'' want, and to insure their safety, they run away from commitments and relationships, they do magic tricks, watch television, buy clothes, quote Shakespeare - anything to escape entanglements that might prove emotionally damaging. Most of all, they like to tell terrible jokes and play little words games: ''I long for you, I short for you, I wear shorts for you.'' It's like a nervous tic, this impulse to blurt out something silly - a way for Miss Moore's characters to short-circuit possible connections.

When her people do make an attempt to talk to one another, their conversations sputter out in gasps of non sequiturs or cliches, or their sentences simply hang there, in the air, dangling and incomplete. In ''Amahl and the Night Visitors: A Guide to the Tenor of Love,'' a couple, on the brink of breaking up, continually mishear one another: the narrator says, ''I usually don't like discussing sex, but. . . '' and her boyfriend snaps back, ''I don't like disgusting sex either.'' Later, their tentative efforts to resolve matters dissolve into a discussion about a MacNeil/Lehrer television program about the consequences of nuclear war. In ''The Kid's Guide to Divorce,'' a girl and her recently divorced mother sit in front of the television, watching late- night horror movies and pointedly not speaking about the dissolution of their family. And in ''Go Like This,'' a woman dying of cancer announces that she intends to kill herself, and her smart, self-conscious friends can only respond with remarks like ''suicide can be, often is, the most definitive statement one can make about one's life.''

Like her characters, Miss Moore possesses a wry, crackly voice, an askew sense of humor and a certain reticence about emotions - qualities that lend her fiction a dry, almost alkaline flavor. In keeping with the title of this collection, several of her stories (''How to Be an Other Woman,'' ''The Kid's Guide to Divorce,'' ''How,'' ''How to Talk to Your Mother (Notes),'' ''Amahl and the Night Visitors,'' ''How to Become a Writer'') take the form of a ''how-to'' manual, told in the second person; and some also employ a diary-like structure - narrative strategies that keep the reader at a distance, while at the same time allowing the author to eschew more traditional story-telling conventions.

This approach results in some fine, funny and very moving pictures of contemporary life among the yuppies that help establish Miss Moore as a writer of enormous talent. Given her gifts - her sharp eye for absurdity, her keen prose - one can only wish that she would release her lyrical gifts more often from her straitjacket of cool decorum, that she would play around a bit more with other narrative forms. There is a sameness of tone to many of the stories in ''Self- Help,'' and the weaker ones resemble those amateur works of sculpture, made of found objects, welded together into an interesting, but jumbled, assemblage - though individual anecdotes and observations are amusing and well-crafted enough, they fail to come together to form a coherent work of art.

While the heroines or narrators of each of the stories in ''Self-Help'' have different names, they might well be the same woman - a smart, fairly hip young woman, so bland in looks that she is always being mistaken by others for their sister or, maybe, Tricia Nixon. At once insecure and terminally self-absorbed, she is someone who must filter everything through the lens of her own ego - ''Reagan is elected President, though you distributed donuts and brochures for Carter'' - and she consequently spends a lot of time looking at her reflection in shop windows, trying to recognize herself.