Sit back, relax, and go shopping -- in a catalog

One busy suburban Chicago wife, mother, and grade-school teacher lives only five minutes from a large store-filled mall. But to shop for everything from plants to clothes, she'd rather stay home. Thumbing through mail-order catalogs, she phones in her purchases at almost any hour of the day or night.

A self-described ''catalog queen,'' she often receives as many as a half-dozen catalogs a day. Though her postman sometimes groans under the load, she insists her method of shopping not only saves her gas and time (''you can flip through catalogs while you watch TV or open the mail''), but allows easy comparison shopping when similar catalogs are studied side by side.

She is convinced the service she gets is every bit as good as what retail stores are offering. When she hesitated on the size of a blazer she was ordering from an Oregon catalog the other day, the order-taker suggested she go to her closet and measure one she already owned.

''Can you imagine?'' she says. ''In the stores you can hardly get anyone to wait on you - let alone go to the fitting room with you. . . . But here was this darling voice of someone ready and willing to figure out the correct size.''

No question about it. Mail-order catalog firms are out to please - offering everything from 24-hour order-taking to toll-free telephone numbers to money-back guarantees, sometimes even on custom and personalized orders.

And customers are going for the added convenience. Mail-order sales have been growing at about twice the rate of sales in regular retail stores.

The Direct Mail Marketing Association (DMMA) says catalog mail-order sales are growing by 10 to 15 percent a year. About 4,000 firms, including such Fortune 500 companies as American Express, now issue catalogs. Even department stores are sending out more than the usual two or three a year.

''Retailers see catalogs as a way to increase distribution of their in-store sales and not become too geographically defined,'' explains DMMA spokeswoman Donna Sweeney. ''And often it costs only about 1/10th as much to expand by catalog as to open another retail store.''

Several firms with a foot in both sales camps have weighed that option very carefully. Expanding the mail-order side of the business often wins out.

Consider the example of L.L. Bean Inc., for instance, the outdoor sporting-goods firm with one 24-hour-a-day retail store in Freeport, Maine. It is the nation's fifth largest catalog company with about $220 million in annual sales, growing at the rate of about 25 percent a year. When company officials debated how best to expand a few years back, they decided to send more catalogs to a wider audience rather than open more stores.

''The mail-order business has really been our forte, and we decided it was best to stick to our knitting,'' explains Bean spokesman Kilton Andrew.

Edmund Scientific, a firm that sells technical equipment through a catalog of the same name and through one New Jersey retail store, recently reached a similar conclusion. A second catalog under the name of company president Robert Edmund has just been mailed out. Its focus is on health-care products, from diet computers to indoor jogging machines.

''The whole idea was to try to expand the market to people we didn't reach before,'' Mr. Edmund explains. ''It's always tempting to expand retail operations. But it's a lot less frightening to start another catalog than open another store.''

What sells particularly well in catalogs? Unusual products not always available in stores and which tend to photograph well, say catalogers.

''When electronics people show us their product lines, we often ask what products retailers aren't showing much interest in,'' says Mr. Edmund, who also happens to be chairman of the DMMA catalog group. ''We can identify the unique features of the product, put it in the book, and make it work.''

New York-based Lillian Vernon, a family-owned, strictly catalog business that specializes in decorative home products and gifts, often designs its own wares and orders them from overseas for better value.''

A major reason for our growth [sales expanded one-third last year] is that we offer things you can't find anywhere else,'' says senior vice-president of marketing Fred Hochberg, who also credits the fact that the company is privately held. ''We're able to take greater risks and make decisions more quickly. If everything doesn't exactly come across, we don't have to answer to public shareholders.''

Most companies are sending out a larger number of lighter weight, more frequent, more specialized catalogs than they used to. Competition, increasingly sophisticated mailing lists, and close monitoring of sales response are the spur. As one issuer says: ''People tend to throw catalogs away faster, so you have to issue them more often and advertise more to keep your name before the public.'' Even Sears, Roebuck & Co., which put out one of the first mail-order catalogs in the country, as hefty as any big-city phone book, last year began issuing smaller catalogs in such specific lines as gourmet cookware and home health care.

''We'll continue as long as we find it's beneficial to us,'' says Sears spokeswoman Kathy Gucfa, who notes that catalog shopping accounts for a steady 22 to 24 percent of the company's business.

''More catalogs are focusing on specific lines rather than a soup-to-nuts merchandising mix,'' confirms DMMA's Donna Sweeney. ''It's essentially just more efficient marketing.''

With the availability of increasingly sophisticated marketing tools, some catalogers such as Spiegel Inc. are targeting higher-income catalog customers. In the mid-1970s the company decided to do away with some 250 catalog-order stores and such items as tires and unpainted furniture. Now it carries designer clothing and advertises in such publications as Vogue and Harpers Bazaar.

''To rebuild the business we had to lose customers, but now we're back in the growth phase,'' says marketing vice-president Edward J. Spiegel.

What about those vastly expensive items that seem designed more to create an image than build sales? On the cover of a recent catalog, Hammacher Schlemmer, for instance, features a $3,600 popcorn vending machine that promises to make enough popcorn for a party of 12 in three minutes.

''We're consciously looking for something eye-catching and a little more expensive,'' admits Mary Geisler of the firm's New York headquarters, who insists that such items do sell. She notes that several catalog-featured mini-Corvettes, which are one-third normal size, operate on a one-quart tank of regular gas, and have been featured for some time in the company catalog at $1, 000-plus, have been sold despite their high price tag.

With more companies vying for each mail-order dollar, many veteran catalogers have found the going noticeably tougher.

''You have to spend a lot more money to get one order,'' says Jane Willson of Georgia's family-owned Sunnyland Farms Inc., which sells fruits and nuts by catalog. ''It gets harder and harder to get a response from any one mailing.''

Though catalog customers must depend on imagination and trust, hoping that they get what they think they see in the picture, returns of mail-order merchandise averages a reasonably low 5 to 10 percent.

''The real mail-order buyer is willing to take the chance of having to return something,'' says Donna Sweeney. ''It's inconvenient, but it may be less so than going to a department store in the first place. There are trade-offs.''

For all their success these days, most companies are watching their finances very carefully. Many, like L.L. Bean, which nets most of its orders by mail rather than by phone, do not find it worthwhile to invest in a toll-free ''800'' number. Many customers, they find, are willing to pay for the added convenience of phoning.

''I never send in orders by mail,'' insists the catalog-rich suburban teacher. ''Filling out all those little forms is too much like paying bills.''