TAGGING ALONG after Howard Goldberg as he leads a rhapsodical exploration of midtown Manhattan's once-notorious Hell's Kitchen area, where he lives, you are apt to end up talking to his neighborhood grocer. Which, in fact, is what he intends, since he considers his fellow New Yorkers -- the people themselves -- the city's untapped tourist attraction.

Most visitors to the nation's leading city wind up meeting only cabbies and hotel clerks, perhaps out of a misconception that New Yorkers are unfriendly. In truth, says the native-born Goldberg, they can be very helpful and love to talk about their hometown. For the past 20 years, he's been leading walking tours up and down his island introducing visitors to the everyday folks who live there.

His firm, Adventure on a Shoestring, is one of a number of sightseeing services that offer specialty tours of New York City for behind-the-scene glimpses of what makes it the nation's capital of theater, art, fashion, design, food and finance. Talk to a ballet star, watch a Seventh Avenue fur designer create a coat before your eyes, discover the real Brooklyn and Flatbush, sample the Lower East Side's delis on a day-long noshing jaunt from pickles to pastries. There's even a once-in-a-while tour down the city's "mean streets."

As the lyrics go from "On the Town," Broadway's ode to itself, "The Bronx is up and the Battery's down," and a whole lot is happening everywhere in between.

Frequently the specialty firms are one- or two-person operations in which a professional in the design, theater or art world supplements income by leading very personal tours to the lofts, studios or stage productions of friends and acquaintances. As such, they provide an opportunity for an insider's view not ordinarily available to most tourists. As one painter/tour leader says, "If I meet an artist friend on the street, I introduce her to my group."

After you've seen New York's top 10 attractions, "then what?" asks Shoestring's Goldberg, who answers by scooping up groups and heading for such diverse neighborhoods as the Lower East Side, Chinatown, Greenwich Village, artsy SoHo, the Broadway theater district, Wall Street and Roosevelt Island. They are mostly two-hour walks that end at a local restaurant, where his charges soak up the ambiance while he answers questions.

On a recent ramble through the midtown area once known as Hell's Kitchen (roughly between 30th and 59th streets and 8th Avenue west to the Hudson River), Goldberg, 53 and at no loss for words, arranged for chats with a clergyman, a worker in a settlement house and one of the countless residents of the area who make their livelihood in the theater. The storekeeper was a spontaneous sidelight.

"It's much more interesting to talk to people who have lived in the place," he says. By the end of the tour, visitors "have an idea of what it was like like--past, present and future." One stop was at St. Malachy's Church on West 49th Street, an actors' chapel, where one-time stars Don Ameche and Pat O'Brien were members of the parish.

Though once a rough gangland neighborhood of distilleries, factories and slaughterhouses--and home of the famous Stillman's Gym, where as a kid Goldberg watched top-name boxers working out--it is rapidly undergoing major redevelopment with hotel, office and theater construction. At the same time, it is a community. "People know each other," he says. "That's why I chose to live there."

Like Goldberg, many of the speciality sightseeing firms aim for groups of at least 10 to 12 people (though occasionally an individual tourist by asking can hitchhike along). The groups arrive in the city as conventioneers, or part of a package tour set up by a travel agent, or students on a class outing. At least one women's club from Washington annually charters a bus north for the weekend as an organization fundraiser.

Often an individual can squeeze into Backstage on Broadway's daily lecture tours of an active Broadway theater. Visitors won't meet the cast or see a performance, but they will hear a stage manager, director or other professional describe how a play is put together, rehearsed and kept vibrant if it turns out to be a long-running hit. Backstage they will see how lighting, props and curtain are coordinated and, maybe, glean a piece of show-biz gossip.

On the other hand, painter Pamela Tudor of Tours de Force Events, whose focus is on "the creative life" of New York, has a friend in the Broadway production of "Foxfire," starring Hume Cronyn, Jessica Tandy and Keith Carradine. As a result, a group of college drama students from Texas she was guiding was invited to stay after a performance one night, and the whole cast came back on stage at the Ethel Barrymore Theater to answer questions. "That doesn't happen with the big tour companies," she says.

For about $300 a day, Barbara Guggenheim of Art Tours of Manhattan will share her detailed knowledge of the city's art treasures with you privately--or in a group to spread the cost. She is a docent at the Whitney Museum of American Art, has a doctorate in art history from Columbia and has been conducting tours through her firm for seven years. Recently one family arranged a five-day, custom-designed immersion into the New York art scene from the Metropolitan Museum to artists' studios in SoHo and TriBeCa. At tour's end, Mom and Dad handed out a special allowance so the youngsters could make an art purchase based on what they had learned. Guggenheim already has 60 groups lined up for trips through the Met's show of artworks from the Vatican.

Visits to the home-furnishings showrooms--generally open only to decorators, architects and others in the trade--is the specialty of Doorway to Design, run by Sheila Sperber, herself an interior design consultant. With the latest design and crafts work in America as backdrop, she conducts an informal seminar in how to incorporate the various styles in the home. "I try to convey the message that with just a few ideas from professionals, they can make exciting changes in their home."

If a fur coat is high on your dream list, follow Gaile Peters of Inside New York into the workroom of a manufacturer and "watch pelts being transferred into a glamorous coat." Once a public relations specialist in fashion, for the past seven years she has been leading tours into the showrooms, design studios and cutting shops of the Seventh-Avenue fashion industry. Sometimes a trip can be combined with shopping at a discount. A tour may include visits to two or three manufacturers--a giant in the lingerie business, for example, and maybe a newcomer in sportswear. Talk to a designer and, if you are lucky, see a sample creation being stitched together, from which 30,000 replicas will be cut for sale.

Harlem is a fascinating and historic area of New York, but not usually one on the must-see list of many city visitors. "Is it safe?" is the most-frequent question asked Antoinette Major of Penny Sightseeing Co., which since 1965 has been scheduling several weekly bus tours, "Harlem As It Is," of the country's largest black community. Once on board, she says, visitors (most of whom are European) are "fascinated by how calm things are."

The bus passes by the site of the Apollo Theater, where many of America's black entertainers got their start, and a former home of Alexander Hamilton. There's a stop at the Schomburg Center for Research in Black Culture on 135th Street and the Jumel Mansion in Washington Heights, where George Washington planned his strategy against the British. The tour also looks at high-income sections as well as the tenements, the burned-out buildings, even a neighborhood made "unsafe" by drug traffic. But "we also take note of all the churches on every corner that keep the community together." The Thursday bus makes an extra stop at one of them for a gospel concert.

Brooklyn, the hometown of Lou Singer, is another famous New York name off the normal tourist path. But since 1970, Singer, a home-delivery distributor for The New York Times who formed Brooklyn Tours, has been luring busloads of visitors across the bridge to see "Beautiful Brownstone Brooklyn," "Fabulous Flatbush" (a Dutch settlement in the 1600s; on one historic house, Hessian soldiers left their names scratched on the window during the Revolutionary War) and "On the Trail of Tiffany" (many of the firm's 19th-century stained-glass works survive in churches, institutions and homes). On its own, Singer notes, "Brooklyn is a very major city."

While all of these tours originate in New York, the Resident Associate Program of the Smithsonian Institution regularly offers weekend educational tours to the city from Washington, many of them focusing on art, open to nonmembers at a slight additional cost. On March 4 and 5, the subject is opera, with performances at the Met of Cilea's "Adriana Lecouvreur" with Renata Scotto and Strauss' "Arabella" with Kiri Te Kanawa, plus a lecture, a reception, a backstage tour of Lincoln Center and two meals "at restaurants frequented by opera buffs." The fee is $235 for members and $258 for nonmembers, including a room at the Barbizon Plaza Hotel. Subscribers get to New York on their own. Soon to be announced for May is a ballet fan's dream tour: a walk through the rehearsal studios of the American Ballet Theatre, tickets to a performance and a opportunity to meet the company's star and leader, Mikhail Baryshnikov.

Not to forget a very special attraction of the metropolis--its ethnic foods. Even Lou Singer can be drawn from Brooklyn to lead his daylong "Noshing Tour" of the Lower East Side, a sampling of specialities in a dozen or so cafes, delis and bakeries. "Guaranteed to put weight on you," he says, even though it's a walk of several blocks. "Within one square mile of Manhattan, one can nosh one's way around the world."

Begin at Gertel's Bake Shop on Hester Street, for hot buttered rolls, pastry puffs and coffee. Onward to bagels and lox, baked vegetable and cheese loafs, tasting samples from Manhattan's last winery, Chinese dim sum at the Silver Palace (praised by France's famed food critics Henri Gault and Christian Millau), the chopped-liver combo platter at the Second Avenue Deli and, as he says, much more. The last stop: Veniero's (Italian) Pastries (since 1896), and Singer's personal favorite, the chocolate velvet mousse--"a mortal sin."

As the Broadway song says, "New York, New York. It's a hell of a town."