As she neared retirement seven years ago, Dora Back of Fords, N.J., decided to start her own business to supplement the income from her secretarial job. She advertised her After Six typing service on community bulletin boards, built a clientele, and began to acquire equipment bought out of earnings from the business.
The typing service mushroomed. Now, since retiring from her regular job, Mrs. Back employs independent contractors and works flexible hours. Her husband, Michael, who retired this year, works with her full time after going to school to learn professional typing.
''We enjoy the business,'' Mrs. Back says. ''It brings in some extra money, and we meet different people. Right now we are not trying to expand, we just want a little something on the side.''
Working people at all stages in their careers are starting home-based businesses. They may want to spend more time with their families, enjoy more flexible schedules, earn a living creating products that give them satisfaction, or simply make ends meet.
''The prime consideration today is survival,'' says Marion Behr, president of the National Alliance of Homebased Businesswomen, who believes the tight job market has contributed to the growing number of home-based businesses.
Census Bureau figures show more than 2 million Americans are home based in their work. From 1970 to 1980 there was a shift in the economy toward more self-employment, according to the ''The State of Small Business: A Report of the President'' released last month by the US Small Business Administration. From 1972 to 1980, the female share of self-employment increased by 60 percent. Today , sole proprietorships account for 75.5 percent of all businesses in the United States.
Whether pursued as a full-time venture for total support or as a means of earning extra income, many small businesses begin in the home. Budding entrepreneurs find they can try out a new business idea on a small scale with a relatively modest initial investment and low overhead. Mrs. Behr cites other advantages: Home-based business people save commuting time, can work when their energy levels are high, and do not have to invest in a working wardrobe.
Home businesses are attractive to mothers with young children at home or in school, or to those who want to help put an older child through college, says Mrs. Behr, co-author of ''Women Working Home'' (WWH Press, Norwood, N.J., $12.95 ). In a home-based profession, child care or looking after elderly relatives becomes greatly simplified. Working at home can also be a good choice for single parents raising children, for retirees, or for married couples who want to work together.
Before starting a home-based venture, Mrs. Behr suggests contacting an attorney, an accountant, an insurance company, and a banker for professional advice.
People working at home must find a location that the family respects as a work area, she says, and they must learn how to deal with isolation, household demands, and interruptions, such as neighbors who drop by in the middle of the day.
Personal computers and telecommunications have opened up new opportunities for work in the home, particularly in service-oriented professions. Mrs. Behr also sees a growing number of partnerships that combine both financial resources and special talents.
Belinda Dennis and Linda Baddaril of Marblehead, Mass., joined forces last November in a small shop called Chocolate Etc., where they sell handmade European-style molded chocolates and dessert pastries.
Both women had been working out of their homes when they decided to go into business together. ''I thought it would be a novel idea to combine chocolate and pastry under the chocolate theme,'' says Mrs. Dennis, wrapping a shell-shape sweet.
So far, their dream has translated into long hours, but customer responses have been gratifying. ''You have to have a lot of initiative,'' Mrs. Baddaril says. ''It all boils down to energy and commitment.''
Parents who work at home find their businesses can foster family solidarity.''All along I've wanted to be close to the children,'' says Audrey Nelson of Goshen, N.H. ''When they were growing up, it was important for me to stay at home.'' The family crafts business has been the Nelsons' sole means of support for 15 years, since her husband, Chuck, left his job at the Massachusetts Institute of Technology. At their studio, Nelson Crafts, the family sells a wide variety of crafts, including ceramics, weaving, paintings, and woodworking.
Through the years their four children were involved in the family business to varying degrees. Mrs. Nelson says the professional interest has given the family another level to communicate on. ''It's been a good experience for all of us, and it's been broadening for the children,'' she says.
Now that the children are college age and older, at least three of the four plan to rely on their creative talents for their livelihood.
''To make it in crafts is not easy,'' Mrs. Nelson says. ''It's a very, very serious business. It's competitive, and the hours are long. But I feel fortunate I've been able to do what I like to do and earn some dollars doing it.''
''You have to give up a lot - the more expensive indulgences,'' adds Mr. Nelson, who makes looms and other objects from wood. ''The reward is: I don't have to answer to anyone. My achievements come from my heart.''
Children's clothing designer Marion Donohoe of Cambridge, Mass., who specializes in smocking, also started her business so she could spend more time with her three children. Although she still works part time in a fabric shop, Mrs. Donohoe expects to be completely home based in the near future.
Her two older girls, ages 6 and 9, both sew themselves and have offered ideas for smocking designs that Mrs. Donohoe has incorporated into the clothes.''
They take an interest and chat while I smock,'' says Mrs. Donohoe. ''They feel they're a part of what I'm doing, and that's special for them.''
Mrs. Donohoe, who began selling her children's clothes three years ago, didn't turn a profit until she took courses at an adult education center to learn basic bookkeeping, marketing, and pricing techniques. ''Until then I didn't know if I was making money or if it was just a hobby,'' she says.
Mrs. Donohoe scouted out local stores as possible outlets to see if her work would fit with their merchandise and checked prices of comparable items. She built up a portfolio of samples, photographs, and sketches to help market her work. She also timed her work to see how long it took to complete an outfit and learned to price her clothing according to both quality and labor.
''You have to think the whole thing out,'' Mrs. Donohoe says. ''Two important things I've learned are: Don't undersell yourself and don't let anyone talk your price down.''
Currently she sells her work through four stores in the Boston area and is still able to keep up with the demand. ''I may have to take on sewers as the business expands - maybe in another year. I am purposely keeping the business at a certain level so I don't overextend my commitments.
''Any woman who has children and wants to have a home business should realize it can work, but it won't happen overnight. It's wonderful while you're working through it. I wish I had had the confidence to start sooner.
''Sources of information for starting a home business include:
* ''Worksteads: Living and Working in the Same Place,'' by Jeremy Joan Hewes (Dolphin Books, Garden City, N.Y., $10.95).
* ''Women Working Home, The Homebased Business Guide and Directory,'' by Marion Behr and Wendy Lazar. Send $12.95 plus $1.25 for postage and handling to PO Box 237, Norwood, N.J. 07648. New Jersey residents must add $.78 tax.
* National Alliance of Homebased Businesswomen, a nonprofit professional organization with chapters nationwide. Membership is also open to men. Contact: NAHB, PO Box 95, Norwood, N.J. 07648.
* A series of useful booklets on starting a business and on specific careers supplied by Bank of America. For a free catalog write to Small Business Reporter , Bank of America, Department 3401, PO Box 37000, San Francisco, Calif. 94137.
* Check with a local office of the Small Business Administration for publications, loan programs, and classes and business seminars in your area. Or write: Small Business Administration, 1141 L St. N.W. Washington, D.C. 20416.