Boston — For two years, Elaine Ross went home from her job as a legal secretary in Lafayette, Ind., got out her watering can, fertilizer, trowels, and other tools, and began work on her second job, tending small trees and plants. Many of those plants were destined for offices and lobbies in the Lafayette area, where businesses and shopping centers leased them from her.
Having grown up on a farm, she was familiar with what it takes to make things grow. With a husband who is a researcher for an agricultural chemical company, Mrs. Ross had access to plenty of information on how to keep the greenery green.
Today, Mrs. Ross no longer works as a secretary. Since 1981, she has been tending her plants full time. She also makes and sells silk and dry flower arrangements.
For Mrs. Ross, the part-time job - which started as a way of turning a hobby into extra income - became a full-time occupation. But for millions of other people, the need to bring in additional income requires them to continue ''moonlighting'' in a second job, perhaps for years. It might be a job working for another employer, but it could also involve free-lancing from home, finding ways to turn a hobby or craft into a money-producing operation, or sharing their knowledge with others, perhaps by teaching a course related to their occupation or some special interest.
Over 4 million people work at more than one job, according to the Bureau of Labor Statistics. And that's just the hard numbers. The ''soft'' numbers include people who do something to earn a little extra money in their spare time and report it on their income tax forms - as well as those who earn a little extra and don't report it.
The reasons for earning extra income are often as varied as the ways people go about it, but they can be as basic as making sure the family has enough money to live on, or earning enough to pay for vacations that are more adventurous than a trip to the seashore. People also moonlight to earn money for investments, to have more clothes, or to pay for higher education. Then there are people who don't do it for the money at all; the hobby is something they enjoy and it just happens to bring in extra money.
''Second-income jobs are not a big part of the labor force,'' says Audrey Freedman, a labor economist at the Conference Board, a business-sponsored research firm. ''In some ways, it's not big enough.'' By this she means that while many people are finding ways of earning additional money, many more ought to be doing so, especially as the median age of the population increases and more workers are faced with early retirement.
Many part-time jobs, Ms. Freedman says, can become full-time after retirement , when there is more time to do things like make craft items, run stores or restaurants, teach, write, or tend plants.
But in those years when one person is still doing two or more jobs, one of the biggest challenges is the loss of free time.
''I can't deny that you give up free time,'' says William Whalen, director of publications at Purdue University. ''You can't do certain things others are doing.'' In addition to his job at Purdue, Mr. Whalen is an active free-lance writer, having had 13 books and over 200 magazine articles published. He also teaches a course on free-lance writing at the university.
While he estimates that only a few hundred people support themselves completely as full-time free-lance writers, over 100,000 do so on a part-time basis, he says.
Using evenings and weekends to make extra money requires more than individual dedication, Whalen says. It also helps to have cooperation from your family to find time to pursue the outside work: ''I have a very understanding wife and children.'' When our children were small, they'd be in bed by 8 or 8:30 and I'd get in a couple hours of writing after that. I have also used some of our vacation time.''
Being a free-lancer also means being the outsider in some conversations. ''I have friends who watch football on TV,'' he says. ''I'm using that time to write , so I can't talk about those things.''
The first step to earning extra money is, of course, finding something to do. For some, like Mrs. Ross, the answer lies in an already-acquired interest or hobby.
For example, says Gunta Voutyras, there is money to be made in yarn goods, dolls, potholders, quilts, woodworking, and pottery. Ms. Voutyras teaches a course called ''Marketing Your Craft'' at the Boston Center for Adult Education. She also owns and manages the Scandinavian Yarn Studio, a shop at the foot of Boston's Beacon Hill where craftspeople can get supplies, instruction, and encouragement.
Current fashion often plays a role in what crafts are most marketable, Ms. Voutyras notes.
''Dolls are very popular right now,'' she says. ''Soft dolls and clothes for them are selling well.''
Most people who sell crafts - often through fairs, specialty stores, or flea markets - are very conscious of quality, she says, but they frequently do not know how to put a price on what they make or the service they perform.
''People are always underpricing themselves,'' Ms. Voutyras says. ''They seem to want to give it away. They should find a way of working out cost and time.'' She says her method of doing this is fairly simple. She takes the cost of all her materials - such as yarn, beads, cloth, and wood - and multiplies it by 3.5. So if the materials for one item cost $10, it should be sold for $35. This, she feels, gives a fair reimbursement for use of the shop or a portion of the home, the person's time, and a reasonable profit.
In ''How to Play the Moonlighting Game'' (Facts on File, New York, $14.95), Jay David suggests a more complicated formula, but one that may yield a more competitive price if you need it. The price, he says, should equal your labor, plus overhead, plus materials, plus profit. You will have to do some research in your area to find out what people with similar skills performing similar tasks are being paid on an hourly basis, and you'll have to figure out exactly what portion of your home (including utilities) is devoted to the work. Then add on a reasonable profit, which he defines as anywhere from 5 to 20 percent, depending on the product or skill. Here again, you'll have to find out what others in your area are charging.
Both formulas leave room to reduce the price, which is a lot easier than going up after you discover you are not covering your costs or earning enough to make the effort worthwhile.
''Always start high and give yourself a chance to come down,'' Ms. Voutyras recommends.
If you are not selling a craft or do not want to lock in your free time to a second moonlighting job, how else can you earn extra money? For starters, you could teach what you know. ''Almost all of our teachers are part-time,'' says Elizabeth Sagaser, assistant program coordinator at the Boston Center for Adult Education. Classes on history, photography, basic law, investment, dance, cooking, and foreign languages are, for the most part, taught by people who are working in these fields, on a full- or part-time basis. Many people have experience or skills they can share with others, she says.
Many of the humanities and liberal arts courses offered at the dozens of adult education centers around the country have expanded to include programs that provide marketable skills. The Boston center, for example, is developing a course on how to make money with a personal computer, including how to write off much of the computer's expense on your income taxes.
That course will be taught by Les Squires of Watertown, Mass., another person who turned moonlighting into full-time work. Once, he did free-lance computer work for smaller businesses that needed information and forms typed into master systems. A law firm, for example, may need standard, ''fill in the blank'' forms typed into its computer. Instead of having a secretary spend several hours a day doing this, it will hire someone like Mr. Squires to do it in his spare time.
Squires is still doing this kind of work, but it is now a full-time occupation paying a six-figure income. In addition, he acts as an agent for several people who do the same thing.
His philosophy about this kind of work may be typical of many people who do free-lancing, moonlighting, or whatever to earn extra income. ''This way, you're a contractor, no longer an employee,'' he says. ''The whole notion of working 9 to 5 starts to seem kind of corny.''