An old Yiddish proverb: It's easier to have children than to raise them.

Some Talmudic wisdom: Breast feed your children for two years.

Tip from "The Second Jewish Catalog": "No matter how carefully you plan for the bar mitzvah reception, you'll never have enough potato salad."

There is a Jewish maxim or rule for just about every activity in life. Somewhere within the Bible, rabbinic lore or custom are prescriptions for rising each morning, making wine, naming a baby.The "how-tos" of being Jewish are abundant, but to each new generation, it would seem, they are less compelling and meaningful.

Two young Jews have been trying to change that, and apparently something of their notion has caught on.

Their first "Jewish Catalog," a do-it-yourself kit on Jewish customs and religious practies, has sold over 180,000 copies since its publication three years ago. The new "Second Jewish Catalog" is an even richer resource for bringing alive the traditions of Jewish observance.

For chart lovers, there is a detailed explanation of all movements during worship - the choreography of prayer - from shucking and bowing to rising on one's tiptoes. If you don't know how to get around a synagogue, use the Catalog as a tour guide. How should the Nazi massacre of 6 million Jews be explained to children? How can antiquated divorce laws discriminating against women be modernized, yet kept true to the faith? How does a wayward Jew return? It's all in the book. So are directions for crocheting a matzoh cover for Passover.

In some ways it seems avant-garde: in others, it is very traditional. There are details on birth, adoption, genetic disease, bar mitzvah, honoring parents, sexuality, the Jewish blind and deaf, education, toys and games, prayer and choosing a rabbi. Thoughtful, provocative and funny, with cartoons, pictures, diagrams and even a "Yellow Pages," the Catalog is illustrative of a new generation of committed young Jews.

When they began writing the first catalog, Sharon and Michael Strassfeld were warned it would never sell. "Publishers told us, 'Bring us a cookbook instead,'" Sharon said. After the first Catalog was published, they were intended to write a second one. But letters came in from readers asking for information on other subjects. The second volume was produced, and the third - and final one - is under way. Unlike the others, it will focus on social issues, such as political action, Israel, Soviet Jewry, intermarriage and coversion.

The Strassfeld, both 26, are typical of a new kind of Jew. They live liberal, contemporary lives, but find cultural and religious tradition exciting in contrast to many of their peers who have become so secularized they are hardly identifiable as Jews. An important source for the Strassfeld's identity has been the "havurah," a community similar to an extended family but not a communal household.

The first Catalog grew out of their community in Boston, the Havurah Shalom. For the past two years, the Strassfelds have been in the 25-member Derech Reut Havurah in New York City, meaning "the path of friendship." Each sabbath they borrow the room of a synagogue for workship.

"The idea of havurah as a small group of people teaching each other and not relying upon a rabbi is an idea that is spreading," said Michael.

Once considered countercultural, these communities are springing up all over the nation, and many are linked to established synagogues.

The point, said Michael, is, "No one can be Jewish for you."

"We've been into celebrating a specific kind of Judaism for a long time," said Sharon. While she and Michael grew up in traditional Jewish homes, they no longer identify with a specific branch of the faith. They consider that unnecessary.

"The most important thing a person can say now is that he or she is Jewish. We find our religion the most important thing in our lives. It binds us and gives us wholeness," she said.

The Catalog looks back to the wisdom of tradition and forward to contemporary realities. As an example of its approach, in the chapter on sexuality it says, "As Jews we should assume that there are resources within our Torah tradition for drawing upon the blessing and mitigating the curse of the sexual revolution."

In some cases, history is no help, as the chapter on Jewish singles shows. For if singles looks to the Bible for how to meet a mate, they will find that Abraham, the first Jewish parent with an unmarried child on his hands, commissioned his servant to find a "significant other" for his son Isaac. In those days, the best place was the town well. All humor aside, the Catalog lists agencies geared toward singles and even gives pointers on organizing a singles group.

A lengthy section on making ethical decisions in abortion, enthanasia and other medical considerations probes the irrelevancy of Jewish tradition to some current problems. For example, following the Talmud instruction that "circumcision should not be performed on cloudy days or days when a southerly wind blows" is hardly useful today. Yet a general attitude is offered - while the ancient sages lacked the technological advances that influence ethical decisions today, they had a great deal of senstivity to human needs. "In an age where we are bound by little," the Catalog advises, "being bound by their sensitivities is a good start toward ethical behavior."

The Strassfelds chose 47 contributors based on their special skills, and the chapters reflect their views.

"I don't think anybody practices the whole book," said Michael, a PhD candidate in history at Brandeis University and editor of a Passover Haggadah for the United Synagogue of America, the Conservative movement of Judaism. "You choose what works for yourself."

The hardest religious laws to follow, said the authors, are the "interpersonal ones."

It's easier to break bread than to think about the other person's feelings and try to atone for it inside," Sharon said. She is a freelance editor.

"In the book, there is a tension between being creative and innovative and trying to maintain tradition," Michael said.

"As the Jew Turns," a chapter on the commandment of self-examination and repentance, notes that in mystical lore, spiritual renewal is linked with the attempt to repair the cosmic rip in the world. "Teshuvah," the commandment of renewal, "demands more of the inner self of the Jew than his/her pocketbook, temple affiliation or commitment to the Jewish gastronomic heritage. Teshuvah asks that the periphery be moved to the center, that Judaism become the main axis of your life . . ."

And Teshuvah is what the Catalog is about.