There's something really cool about having a pair of tattered sneakers casually leaning up against the Emmy that stands on the dressing room shelf. Not many 15-year-olds can count prestigious golden statuettes among their possessions.

According to most of those who know her well, Kristy McNichol is an example of everything that is not the stereotyped child star.

Get her to talk about, say, Donny Osmond or John Travolta, and Kristy melts a little -- just like countless other teen-agers. Ask Kristy about her top-rated ABC dramatic series, "Family," for which she won that Emmy, and she is business-like and to the point. But steer the discussion to disco dancing, skateboarding, tennis or motorcycles and she becomes warmly expansive.

For a 90-pound girl who will cash paychecks of more than $100,000 this year and whose weekly mail pull is said to be around 4,000 letters, Kristy remains rather unaffected.

As the tomboy, Buddy, of the successful "Family", which moves to Thursdays on ABC's fall schedule, Kristy has managed to win the respect of even hard-nosed show-business types who view pubescent actresses with the same scorn they'd reserve for an attack of sinusitis. "Family" has been singled out as one of television's better shows, and Kristy's work in the program -- a mix of soap opera and sociologist statement -- has been praised, too.

She recently said she looks at her career as more than a job and a means to fame and fortune.

"If I didn't have all that, I'd still want to be an actress", she insisted. "It's hard work, but I get a really good feeling after I go home. As far as I'm concerned, I'll do it forever. Nothing else has ever really appealed to me except acting." Which is rather interesting, in light of the fact that Kristy has never had an acting lesson in her life. "When I have to cry or do a sad scene," she explained, "what I usually do is think of the time long ago when my pet dog was killed. I can cry then. It's very simple that way."

She also explained she's never had a singing or dancing lesson either, yet her first single record, "He's So Fine," cut with her brother, Jimmy McNichol, sold very well.

The song was a remake of an oldie by the Chiffons, who emerged as the background singers for the McNichols on the disc. (RCA has just released the pair's first album, "Kristy and Jimmy McNichol," which is also expected to do very well." All I have to do," Kristy said, "is watch someone else or listen to music or watch someone dancing. Whatever it is just comes to me. I think if I had acting lessons or a vocal coach, it might only confuse me."

Just about the only problem confronting the young performer is that her career keeps her so busy, she doesn't have all the time she'd like to indulge in such youthful, mundane activities as sports and disco-hopping. Like other "studio brats," she receives instruction from a tutor on the set each day, instead of attending a formal high school. "I like motorcycling in the desert," Kristy said, "and I want you to know I'm very competitive. It comes, I suppose, from having two brothers.I play football, too. I also enjoy skiing." Asked about her musical tastes, she said she likes the Osmonds, Chicago, the Bee Gees and Debby Boone, in that order. "I can't really relate to some weirdo groups like Kiss. Or Alice Cooper or freaky people.

"Family" is back in production now, after its seasonal hiatus, and Kristy is required to be on the set every morning at 7. During the break, she went to Atlanta where she spent five weeks filming an NBC movie, "Summer of My German Soldier," in which she portrays an alienated Jewish teen-ager who befriends a German POW during World War II.

Kristy is anxious to do more movies, although she is unwilling to play certain parts. "I'm given all kinds of movie scripts which really aren't for me. They all imply sex, drugs and booze. It's stuff that I hate when it's presented in some ways. I can't pretend to be that sort of kid." In any case, she doesn't want to play kids for too many more years. "I love comedy and musicals," Kristy said. "I can't wait to be old enough to play romantic roles. Or glamorous parts. You know, the kind where you come out all dressed up and look stunning."