Marla Hanson had never been to New York City, except for a layover between flights once. So last spring, as Hanson prepared to transfer to the Manhattan office of the sportswear manufacturer for which she'd been a sales representative in Dallas, an older colleague who'd been to New York on business trips was worried.

"Before she left, I gave her a list," recalls the woman, assistant to a vice president of J.H. Collectibles. " 'Watch your purse. Don't ask a stranger the time of day. Keep your head down; don't look people in the eye. Mind your own business as much as possible.' " Her coworker fretted about Hanson's naivete'. "She felt like everyone was a good person. She trusts people too much."

The list notwithstanding, Hanson -- whose ambitions for a more glamorous life were finally being realized with a growing list of lucrative modeling and television assignments -- is now getting a different sort of headline-and-flashbulb treatment than she had envisioned.

Early Thursday morning two attackers, allegedly hired by the landlord she'd been arguing with over a security deposit, slashed her face with a razor so extensively that she required 150 stitches during more than four hours of predawn treatment at St. Vincent's Hospital.

Yesterday Hanson, wearing a seersucker robe and baby-blue bedroom slippers, smiled gamely as her wheelchair was pushed into a tiny conference room packed with reporters, photographers and camera crews anxious to continue the now front-page story of the slashed "stunner" and the "hired thugs." "I'm really feeling terrific," she told the press. "I'm real confident I'll be back to normal soon."

Horrified friends who called her room got the same upbeat message: She was fine, she was going to keep working, maybe branch out into acting and television.

But the plastic surgeon who confronted her bloodied face at 1:45 a.m. said yesterday that her scars, though they might be improved in appearance, were permanent and that there had also been some damage, the extent not assessable for months, to her facial muscles. "I have never shivered, looking at wounds, as I did when I looked at her," said Dr. Ronald Levandusky.

One could scarcely invent a more quintessential example of the small-town girl seeking her fortune with her face in the Big Apple. "She probably would have made a wonderful Miss America," says the president of a Dallas real estate firm where Hanson once tried selling houses. "She has a sort of appealing quality, in the way wholesome midwestern girls do," agrees fashion photographer Mark Babushkin.

Yet people who knew her in New York and Dallas also saw a steely streak of determination.

She had, for instance, managed to wangle a few modeling jobs in New York before she had signed with the supposedly essential agency. She had overcome a serious physical handicap -- being 5 feet 4 in a field where the top agencies won't even look at someone under 5-8. And she had probably fudged her age a bit: Her college records show she is 25, but at her agency she passed for 20. She probably would have topped $100,000 in earnings this year, Petite Model Management estimates. Before what Hanson calls "the accident," "she was starting to skyrocket," says Gina Gold, Petite's television coordinator.

Hanson is a honey-blond stereotype, a varsity cheerleader from Odessa High School, in a rural community outside Kansas City, Mo. In 1979 she entered Southwestern Assemblies of God College, where 600 students study the Bible and "general education with a Christian emphasis" in somnolent Waxahachie, Tex. A dean there remembers her as a friendly but quiet, above-average student who left after two years without official explanation and without completing the requirements for a junior college degree.

She apparently struggled for money, working to pay her college tuition. When she moved to livelier Dallas, Hanson acquired a real estate license but despite a boom market and a second, part-time job, she couldn't support herself between sales commission checks.

Her financial status stabilized when an associate's husband hired her as one of three sales reps at J.H. Collectibles in January 1985. But it was clear that she had other plans: she was putting a modeling "book" together. When a similar position opened in the New York office six months later, Hanson grabbed the ring.

Several months later, Hanson showed up at the open interviews held regularly at Petite Model Management, which represents about 25 women who are 5 feet 3 to 5 feet 7. "She walked in off the street, hardly wearing any makeup," recalls Gina Gold of Petite. "She came in with a few little photos, practically snapshots." But once the agency had built up her portfolio, the bookings began to materialize. Hanson's legs were in Mademoiselle and her face will soon appear in Glamour. She made an in-house video for Bali bras ("she looked incredible in lingerie," Gold says). She was an extra in a forthcoming Warren Beatty movie. She's featured in a candy bar commercial about to be aired.

By the end of February, when her Dallas colleagues from J.H. were in town for a sales meeting, Hanson could proudly show them her new portfolio and pass around her ad layouts. "I got the impression that she finally was doing what she wanted, that things were falling into place," said the friend who had provided the cautionary list. "She was real excited."

Still, like other ambitious New Yorkers, she faced the apartment crunch. Until a couple of weeks ago, Hanson and her roommates, also models, sublet a West 34th Street co-op owned by Steven Roth, 28, a makeup man who worked free-lance for CBS. They were just acquaintances, Hanson said at the press conference yesterday. Friends said Hanson was uncomfortable with the fact that Roth kept keys to the apartment she was leasing. But the wrangling apparently began when Hanson moved into another apartment in the same building and Roth, Hanson said at yesterday's press conference, would not return her $850 security deposit.

Hanson told reporters that she had gotten "quite nasty" about the apartment hassle. She was feeling bad about her insistence, she said, when Roth called and said he would meet her at Shutters, a bar on the ground floor of her building, and pay her the money he owed.

"Things come back to you when you're nasty to people," Hanson says Roth told her when they met at Shutters. The police report says only that when Roth asked her to accompany him outside for the payment, two men began to follow them and announced a robbery. It took Hanson a moment to realize that the hands flailing near her face held a razor, and that she was bleeding from multiple wounds. Screaming, she went back into the bar and was taken to St. Vincent's by ambulance.

Shortly afterward police arrested Daren Norman, 20, and Steven Bowman, 27, both of Queens, and Bowman implicated Roth. At arraignment yesterday, the district attorney's office said it would show a grand jury a videotaped confession indicating that Roth had met with his codefendants Wednesday night to plan the "robbery." Charged with assault, Roth was held on $250,000 bail. Bail for Bowman and Norman was set at $100,000 each; they are charged with assault, resisting arrest and possession of deadly weapons. Police also charged Bowman with possession of four vials of the cocaine derivative "crack."

How much Roth allegedly paid the pair has not been determined, a spokeswoman for the district attorney says. But in court Friday, the assistant DA told the judge that Bowman had an "incentive" of particular value in New York: Roth was to give him use of an apartment.

It could be a year, the plastic surgeon says, before it's clear how much damage Marla Hanson sustained Thursday. She has vowed to stay in New York ("I love New York; I'm not going to leave because of this") and to continue modeling. If she can't, she told reporters, she might go back to real estate, or even pursue her interest in painting. "There's so much I could do," she said cheerfully.

But horrible though it may sound, people in the industry say, being "the slashed stunner" could pay career dividends. Hanson has not been particularly reluctant to discuss her ordeal: St. Vincent's officials, surprised to learn that she had permitted a WNBC-TV camera crew to visit her hospital room later on the day she emerged from surgery, suggested a press conference as the best way to handle the deluge of requests. Hanson agreed. She has given several brief interviews to local reporters. She gave photographer Lynn Murray permission to sell photos from a test session they shot last week to newspapers and magazines. "It's unfortunate that this had to happen," Murray said, "but it certainly has drawn a lot of attention."