Just after one of Grace and Fred Hechinger's children narrowly missed being mugged in New York City, she wrote a column in The Wall Street Journal about "how that makes everybody move to the suburbs."

Later, as she went through the experience of bringing up two sons (now 18 and 22) in Manhattan, she realized what she and other parents needed was a primer on steering their children through the perils of urban life, "how to recognize difficult situations, how to avoid them if possible, and, if not, how to react in the safest manner."

Hechinger wondered whether she was being overprotective about some things and not protective enough about others. She pondered what to tell her children about crime and street violence. "There really wasn't much guidance, and it wasn't a subject that was discussed, and yet it was one that I was very concerned about."

A writer specializing in education, family life and women's issues, Hechinger never found the guide she was seeking, so she wrote her own, How To Raise a Street Smart Child: The Complete Parents' Guide to Safety on the Street and at Home (Facts on File, 160 pp., $14.95).

A "street smart child," according to Hechinger, knows the realities of urban living, is not overprotected by parents, knows how to handle him/herself in any situation inside and outside the home, does not look "muggable" and blends in with contemporaries. "A child should be a zebra in a collection of zebras, not a gazelle."

"We cannot make our children completely safe," she says, "but we can reduce the risks by teaching them how to avoid potential dangers and by establishing good communication."

Among subjects tackled in her book: how to deal with muggers, how to cope with school bullies; why and how to talk with your child about sexual abuse; what to do if your child is molested; what to do if your child is missing.

Parents, she concedes, tread a fine line between making children unduly fearful or paranoid about the dangers of city living, and yet aware of potential dangers. "Basically your children will think the way you think. If you think the world is an okay place but there are some bad people in it, some freaks or whatever, that's the way they're going to end up thinking about it.

"I'm a strong believer about parents talking to their children about everything. I'm amazed at how few parents do. It's the best defense a child really has, for you to tell them what to do in given situations, and to rehearse it, to tell them what sex abuse is, to tell them they can say 'No.' Kids feel that everything is their fault if you don't."

What you tell children depends on their age, "but I think you want to start when they're quite small, 3 or 4, and as they get older, tell them more and more. Now I bet there's not a child over the age of 3 that hasn't heard of sex abuse because they all watch television, and they may have all kinds of crazy ideas about it.

"We as a nation," claims Hechinger, "don't care enough about our children in any way." The reason more people are expressing concern about their children, she says, may be attributed to recent revelations of sexual abuse in schools and day-care centers.

"We say, 'Oh, we care so much about our children' and 'Our children are our precious resource,' but actually we don't spend any money on them. Even pediatricians get less money than a lot of other specialists. And most people spend more time picking out a car than they do picking out a school or day-care center for their child."

Among other resources:

* "Child Abuse and Neglect: The NEA Multimedia Training Program." Geared toward teachers, with film strips, tapes and pamphlets on detection, reporting and counseling. National Education Association Professional Library, 1201 16th St. NW, Washington, D.C. 20036. (202) 833-4000.

* "Staying Safe," a new booklet for parents and children compiled by the D.C. Rape Crisis Center. Send $3 check, payable to D.C. Rape Crisis Center, P.O. Box 21005, Washington, D.C. 20009. Authors I. Nkenge Toure and Elizabeth M. Ozer, whose safety and prevention workshops for children and adults are presented in D.C. public schools, will arrange sessions with any group requesting them. Write: Community Education Department, care of the D.C. Rape Crisis Center