Long-range decorating plan allows for gradual updating of first homes

Ninety percent of the couples who come to him cannot describe exactly what kind of decor they want, says Edward J. Perrault, a Houston interior designer who has decorated homes, offices, clubs, and private airplanes for many leading Texans.

Mr. Perrault has helped dozens of young couples establish and develop first homes, a process for which from six months to five years should be allowed, he says. ''We have to help them define and find a decorating style that they will like, and then work out a carefully detailed program that will produce it. It requires much discussion and a vast process of elimination of notions and ideas.''

Some couples, he says, come in with scrapbooks or folders full of magazine and newspaper pictures, color swatches, snips of fabrics and wallpapers. These are helpful, he agrees, and provide a point of departure for discussion. Sometimes the scrapbooks reveal a lot about tastes and preferences. Sometimes, the couple have already outgrown the ideas they have cherished and are willing to move on to newer concepts.

Once living requirements and style have been determined, Mr. Perrault and his staff draw up the plans for the total interior. ''We do a long-range floor plan of what the job will look like completed, with everything in place. We do the plan, the color scheme, and the cost estimates for the entire job. Then we tell them they can chip away at this master plan for months or years, as their income allows.''

He tells them to start with simple backgrounds and a good sofa, and not to insist on instant art on the walls. If they can't wait until they can afford the right painting, he helps them begin with good serigraphs or graphics. And if they want to build a cluster arrangement of art on one wall, he insists that the individual items have real quality, and not just be an assortment put together to take the place of a large painting.

Although Mr. Perrault terms the interior decoration of his own Houston house ''mellow,'' he says he keeps it interesting by updating it periodically, just as he advises others to do.

''Since I prefer the texture and feel of fabric on my walls, I've recently covered bedroom walls in a deep coral fabric, and chosen new fabrics in beiges and browns for my main living area walls. I also like to change my interior plants around seasonally and do some replacing and trying out of new plant varieties.''

Because he loves Oriental art objects from Tibet, Thailand, India, and China, he also, from time to time, adds a few new objects to his rooms. ''I find (that) every small redecoration project and acquisition of a new thing which must somehow be absorbed in the overall scheme impels me to reanalyze my possessions. This process is a good aesthetic exercise and I recommend it to everyone.''

For instance, he explains, when he is rearranging his collections after the upheaval of repainting or recovering the walls, he looks at every object with a fresh eye to ''rediscover its meaning and importance, and why it is a delight to me. ... If I don't react with enthusiasm, I find ways of editing the pieces out of my home, and replacing them with something that I enjoy more. I call this process 'refining' and tell clients that it is one of the pluses of keeping small decorating jobs going. They keep you alert as to what you have and where it is, and to what you might like to change.''

If there is a ''typical Houston look'' in interior design, Mr. Perrault thinks it would blend the sophistication of the East Coast and the casualness of the West Coast. It might include some beautiful wood-paneled walls, travertine marble floors, and contemporary seating pieces mixed with good antiques.

What he has noted most in his years of decorating is the fact that so many Texans have developed a taste for both antiques and works of art. He says one of the first questions that new clients put to him and to his staff is how best to hang and care for their art. The second concern (if they do not already own antiques) is guidance in acquiring a few fine English, French, or Oriental specimens.