The house was "hospital-clean," but for two months real estate agent Ronald W. Jensen was unable to sell it. The problem: The house smelled like a hospital. His solution: Having its owners bake bread 15 minutes before the open house.

It "sounds silly," says Jensen, but the aroma gave the house a cozy warmth, and it sold that day. In the real estate business for 14 years, Jensen has turned his experience into a how-to book for people who want to sell their homes themselves and save thousands of dollars in real estate commissions.

With today's inflated prices, the $40,000 home you bought several years ago may be worth $100,000 or more now. At 6 percent of the sale price, the real estate agent's fee for handling the transaction would be $6,000. Why not pocket most of that money yourself? he asks.

Want to add a mellow mood to your home? Play soft music in the background and, if it's cool outside, light the fire. "Everybody seems to love a fireplace," he says. Don't turn on the TV set-the buyer may pay more attention to it than to your house.

Almost anybody should be able to sell his own home and often do it as fast as an agent, says Jensen, who was in Washington recently to promote his book. But most people are afraid to try because they think they have to be experts. Not true, he says. Selling a home "is not a great big mystery."

"The house sells itself," he says. You don't have to be a super salesman. On one occasion, recalls Jensen, 40, who owns his own firm in New Berlin, Wis., he followed a client quietly through a house and got the signed contract without uttering a word.

The time not to sell your home yourself is when you've taken a new job out of town and want to make the transfer immediately. It's better then to have someone else do the work for you, says Jensen.

Jensen's book, "Sell Your Home 'By Owner' and Save the Commission" (Warner paperback, 184 pages, $4.95), began as advice pamphlets for his clients and grew from there. "I got fed up with telling people how to clean up their house" before prospective buyers arrived.

Jensen offers these basic tips for the do-it-yourselfer:

Hire a professional appraiser and a good attorney experienced in real estate transactions. They should be the only professional help you'll need.

Make the house as "neat and clean and presentable" as possible. Wash windows, clean the peanut butter off door knobs, remove clutter from the garage. If the closets are full, pack away some of the clothing; it makes the closets look bigger.

Prepare a data sheet listing the property's vital statistics (including a photo) and get it duplicated to give to prospective buyers.

Place a professional-looking sign ("For Sale by Owner") on your lawn. Forget the handpainted cardboard on a stick. A sloppy sign, Jensen says, "reflects somewhat on you and your property."

Take into account the differences in buyers. Some may try to cheat you. Others may be "green" at house-hunting and need to be helped. Lead the novice into a room and open the closet doors yourself.

Don't misrepresent your home (though some puffing is to be expected). It can get you in legal trouble.

Jensen cautions that the minute the real estate agents learn your house is up for sale, they'll be lining up at your front door. Tell them, "We're doing it ourselves, he says, and not to contact you for two months or you won't consider their help if you should need it. CAPTION: Illustrations, no caption, From the book