By lunchtime yesterday -- the second day of the two-day conference on "The Business of Art and the Artist" -- at least one participant had put the new-found knowledge to work: "Hang onto your lunch receipts, folks, they're deductible!"

She was one of 125 Washington visual artists who had paid $20 to $35 (also deductible) to learn how to become more professional, aggressive and successful entrepreneurs. "This is the sort of thing they never told us in art school," said painter John Pass, who with most of the other participants found the conference "invaluable, tremendously helpful."

"Artists need to be more sophisticated about things like lawyers and accountants, and we're here to raise their consciousness," said Lee Evan Caplin, assistant to Livingston Biddle at the National Endowment for the Arts, and moderator of the event, which took place in the Labor Department auditorium. "This is part of NEA's ongoing attempt to find ways to help artists, apart from our grants." To this end, in 1979, the NEA and the Small Business Administration each contributed $15,000 for pilot conferences in Los Angeles, Chicago and New York, which drew a thousand artists each.

The Washington conference -- organized jointly by the Cultural Alliance of Greater Washington and the Small Business Administration -- is the first in an ongoing program of similar conferences in every state and territory over the next year, potentially affecting thousands of artists. In each case, different local sponsors and speakers will be found by the SBA, which has long offered aid to other small businesses, though never to artists.

Monday's program consisted of a parade of tax lawyers, copyright lawyers, patent lawyers, insurance moguls and grant-givers who tried to arm the mostly young, inexperienced group of visual artists with hard facts on subjects like contracts, taxation and record-keeping and estate planning.

Among the more surprising revelations was the increase in unconventional outlets for exhibitions and sales that have developed over the past few years, among them banks, law firms, architects, landscape architects, restaurants, hotels, condominium and shopping-center developers. Names and phone numbers were recited by Ann Van Devanter, director of cultural affairs for Chevy Chase Savings and Loan, and Becky Hannum, "Art in the Marketplace" coordinator for the Rouse Company, both of whom brought enthusiastic applause. So did chairmaker Peter Danko, who explained how through his efforts his chair had become part of the permanent collection of the Museum of Modern Art, and the design subsequently sold.

Yesterday's events were divided into two parts -- "bullets" and "targets," as Caplin put it. He meant the preparation of good slides, concise resumes and neat and tidy portfolios with which an artist must arm himself before hitting his target -- the dealers and alternative outlets for art.

After a highly informative presentation by photographer Steve Abramowitz on "How to Photograph Your Art Work," a panel on marketing art featured presentations by dealer Chris Middendorf (don't walk into a gallery cold, make an appointment, he advised) and Bodil Meleney, executive director of the D.C. Slide Registry of Women Artists -- which for $15 will keep on permanent file the slides and resume of any area artist or craftsperson (men are also included) who submits slides.

Several similar conferences have been turning up here and elsewhere. The Ellington School of the Arts organized one last spring, and the 1980 version of the five-year-old Washington Women's Arts Center seminar on "Understanding the Art World and Making It Work for You" gets under way this week.

According to Jenne Glover, a fabric artist now showing at Raku gallery, her career was launched last year after an Alliance-sponsored seminar. "I'm in love with the Cultural Alliance," she said, adding, "everything that has happened to me has happened because of them." She currently has shows booked through spring.