IT'S SO MESSY," said Choo San Goh, smiling in only half-feigned despair. "I can see I'm going to have one of my sleepless nights again." The young choreographer was speaking of his new ballet, "Double Contrasts," to the music of Poulenc's Concerto for 2 Pianos and Orchestra, to be premiered today by the Washington Ballet at Lisner Auditorium.

It was midway in a 2-hour rehearsal, after a month's intensive work. "Look, there's Maya," he said, indicating Maya Larson, a 16-year-old dancer of soft, big-eyed countenance who is one of the two female principals. "She's still so young, her eyes are always down to the floor. I keep saying, look up, look up. She came to me the other day crying, 'I can't do this step, I just can't, it's too hard.' Go have a good cry, I told her, and you'll do it."

Still, there was little rational cause for discouragement. In fewer than two years in Washington, Goh has produced five new ballets for the troupe - "Double Contrasts" will be the sixth - and restaged three earlier ones, all of which together have become the backbone of a much strengthened company repertoire. And the core of the company's 15 dancers, a third of them now male, has been performing with increasing galvanic concentration and style.

Audiences have been enthusiastic and so have reviewers. But despite the artistic strides - and lacking the prestigious stars or the glamor of a Kennedy Center setting - there are still empty seats at its Lisner Auditorium concerts. Choo San Goh and the Washington Ballet have been more quickly appreciated outside their home ground.

After the company performed Goh's ballets at a regional festival in Georgia last year, for example, the codirector of the Royal Danish Ballet, Kirsten Ralov, invited him to create something for her own company. Rober Joffrey, who was also at hte festival, has arranged for Goh to amoun a new piece with Joffrey II company for the opening this November of that troupe's New York season. This fall Arthur, Mitchell's Dance Theatre of Hariem will stage teo Goh ballets. The Pacific Northwest Ballet in Seattle will be performing his "Variations Serieuses" next month. In june, he'll create a new work for the Pennsylvania Ballet's apprentice group - with a grant of $1,800 form the National Endoement for the Arts. Next spring, he'll make still another new ballet for the Housten Ballet, during a two-month residency there.

That kind of attention is a sign of exceptional promise in the dance world. What attracted Joffrey's eye? "With so many young people cultivating more of a modern dance idiom, Goh has such a fine command of the classical vocabulary, which he uses not only with skill and flair but in a very individual manner," Joffrey explained last week.

Born in Singapore in 1948, Goh was bitten by the bug at an early age, as were an elder brother and sister who founded the Singapore Ballet Academy. Goh studied there and began choreographing whenever he could find the chance - and by the time he was in his teens he's done several pieces for the academy, a TV commerical, and some local opera productions. He also found time to take a degree in biochemistry in deference to parential wishes.

But in 1971 he decided to head West to purse his dance career in earnest, and that same year he was accepted into the Dutch National Ballet. in his five years as a dancer there, he worked on his own ballet composition more or less on the sly, finally winning some "official recognition in the form of grants and performances. Then a fellow dancer in the Dutch company Clint Farha, who'd studied in Washington, recommended Goh to Mary Day, director of the Washington Ballet. Goh eagerly accepted an invitation to join Day's troupe as resident choreographer - it was the chance he'd been hoping for to create new work without hindrance.Be this as it may, there's no evading the labor pains that attend the making of a new ballet. For Goh, work on "Double Contrasts" had to be sandwiched between studio availability schedules, his teaching responsibilities - three hours a day five days a week - rehearsals of his own older ballets and other company repertory , preparing for intervening performances, dealing with the outside world and so forth. And from the premiere of his last new ballet, "Synonyms," to today's Lisner performance there remained a scant six weeks.

Considerate time - until one reflects on how ballets are constructed.

Among the creative processes of the performing arts, choreography is still in the most primitive state - it's pure handicraft, with no labor-saving devices or even the most rudimentary technological aids. A dancer, unlike an actor, has no script to take home and study, and unlike the musician, no score to be propped up as a hinge for memory. Once the designs of the dance have been invented by the choregrapher, in itself a labyrinthine endeavor, they must be taught to the dancers individually and en masse step by step, phrase by phrase, and recapitulated until thoroughly mastered and retained.

Only then can any real artistic honing commence. Under these condition, two hours of rehearsal a day - on available days - over a month and half is hardly ample for a three-movement piece as complex and demanding as "Double Contrasts" turned out to be.

The ballet began to germinate as an idea, as it almost always does for Goh, with the finding of the music. "A friend suggested last September that I try the Poulenc Concerto," he recalls. "I didn't do anything about it, but then on a trip to California I heard it on the radio and loved it immediately. When the season was planned, I had originally intended to work with Emerson, Lake and Palmer's Pirate' recording."

The Emerson, Lake and Palmer didn't go to waste - it became the basis for Goh's "For the First Time," commissioned by Gus Giordano's Jazz Dance Company premiered in Jacksonville this past January. Actual work on "Double Contrasts" started in mid-March.

Gon begins listened to the music hes chosen again and again until it's absorbed into his marrow. By that time, the music has usually prompted a flow of dance concepte in his imagination. in the case of the Poulenc - which alternates from racy, brittle Parisian neo-classicism to sweetly lulling lyricism and back - Goh knew from the start that he wanted the ballet to reflect the duality of the two solo instruments and the dynamic polarities of the score costumes (he designs his own of late) in starkly constrasting ivories and blacks, "like piano keys."

By the time the first rehearsal of "Double Constrasts" was called, Goh had much of the dance combinations for the first movement already fixed in his head, though many details remained to be chiseled out in the studio. At the start, he played the entire tape for the dancers, letting them familiarize themselved with the general outlines of the music.Then he'd replay a small portion from the top, this time demonstrating the sequence of movement that was to go with it, counting aloud the rhythmic groupings. Then the music alone again.

Then, having physically placed the dancers in their opening positions and shaped their beginning poses, he'd go through the sequence once more, with the dancers following behind in a first attempt at "picking up" the steps checking their contours and aligment in the wall-length mirror that's an indispensable ballet studio fixture.

Next dancers would try the same fragment on their own, first without the music, then with Goh sitting in front of them counting, cajoling, correcting Because his choregraphic idiom departs do freely from the classical ballet steps and postions, Goh's verbal indications to the dancers take humming, the funny little hand and arm gesture dancers use as a universal shorthand for body movement, and descriptive words, only occasionally pepered by the French nomenclature of ballet tradition.

"And, one, two, over, step, one, two, pirouette up, the arm this way over the head now, dee-dee dum, dee-dee dum,glissade , step, step, yes, right-glissade, entrechat-six." And so it would proceed.

Every choreographer has his oen methods. Some make elaborate notes and sketches on paper. Marius Petipa, the choreographer of "sleeping Beauty," used to experiment with large ensembles by moving chess pieces around on a table top. Some, like George Balanchine, only really when faced with live dancers. Goh makes only a few notes beforehand, jotting down key ideas, but though he choreographs with particular dancers in mind, he usually arrives at the studio with the framework of the ballet mentally worked out.

During the early rehearsals of "Double Contrasts," some of the ensemble passages, especially the rhythmically trickly ones, would clamber to a halt in giggling chaos, the orderly patterns dissolving into something like a scramble for fumbled football. Repetition was the only cure, with Goh correcting from the sidelines - "Here the leg must go way out to the side, with the foot pointed," or "Be a little more bold with this step - like a tornado, sweeping forward."

Now and then he'd jump up to pull a limb into place or to demonstrate a partnering maneuver, himself playing "ballerina" to get the point across. Occasionally he'd get stuck on the continuation of a phrase, and for a minute or two he'd sit with chin tilted up, his beanpole figure stretched out, his eyes shut and tips pursed.

Before the first week of rehearsal was over, something happened that illustrated the chronic perils of ballet art, dependent as it is on the vulnerable human physique. One of the male dancers was injured severely enough to put him out of commission for weeks, a not common occurrence, especially given a ballet syntax as gymnastically taxing as Choo San Goh's. As a replacement, the choreographer decided to risk it with a gifted young man, John Goding, who had only been with the company since September and had been dancing for a mere two years altogether.

As the weeks passed, one could see the ballet coming into focus, the steps acquiring distinctive character, the rhythms becoming clear, the spatial patterns taking form. It was like watching a photographic print in a bath fusing from an inchoate smudge into a bright picture.

And as the profile of "Double Contrasts" resolved into clarify, it became evident too that this newest Goh creation was to have the same boldness and intefrity that had made his previous ballets so compelling. All the leading GOh traits were there - the ingenious disposition of movement in relation to music; the feeling for the indivuality of the dancers; the cleverly staggered exits and entrances; the lucid developmental logic; the wonderful sense of arrival and culmination at climactic points; and perhaps above all, the strikingly inventive dance imagery.

A number of influences thread their way through Goh's ballets - one can see, for example, the speed and geometrical formations of Balanchine, the oddball wittiness of Robbins, and the anatomical virtuosity of Glen Tetley or Rudi van Dantzig (Goh's mentor at the Dutch National Ballet) cropping up in various ways. yet Goh's work looks neither eclectic nor derivative - it looks always like Goh, and perhaps the chief reason is the characteristic, eye-catching kinetic imaginery he divises.Though the image spring form specific visions evoked in Goh by the music, he's reluctant to talk about them to the dancers.

"I tell them," he says, "feel it in the movement and the music, and the idea will come to you, because I think it's best if they arrive at it themselves. But sometimes when they don't seems to be getting it, I'll tell them what's they don't seem to be getting it, I'll tell what's in my head." Thus there's one passage in which a row of dancers, elbows cocked to the sided, wave their arms sinuously in front of their faces. "I said, this must be like in a car wash, with those tentacles brushing across this way and that."

In another spot, where the women are hauled forward draped across the men's backs, he told the dancers, "It is as if you were pulling a very heavy barge - no reflection on the girls - up-stream with ropes from the shore; I keep hearing that Russian song, 'The Volga Boatman,' at this point." "Double Constrasts" abounds in such imagery. Elsewhere, dancers in a straight rank begin to bend their figures into waving S-shapes, as if they were fronds rustled by a breeze. And towards the end of the ballet, the ensemble swings its arms stiffly in huge to-and-fro arcs to a clanging passage in the music, "like church bells in a tower," Goh says.

The dancers are appreciative of Goh's qualities. As Madelyn Berdes put it, "His movement seems impossible when he first shows so right and so interesting. i really think Choo has been a tremendous spark for the company."

Since he got here, Goh has found little time in his life, aside from occasional concerts, dance performances and TV-watching, for anything else but teaching, rehearsing and making ballets.

The one exception has been his plants. "I'd love to be to do gardening, but it's impossible in my tiny apartment. So I have all these plants, anyway.

"I like to get them and tend them when they're very small - I love to see things grow."