As John Rothchild sees it, homeowners' growing interest in cutting their ever-climbing heating and cooling bills has triggered a deluge of advice. That flood of information has left some households confused over what to do and others with added insulation, elaborate solar devices but still high bills.

To clear some of the confusion and to explain what homeowners can do to help themselves, Rothchild has written "Stop Burning Your Money: The Intelligent Homeowner's Guide to Household Energy Savings," ($15.50) published in October by Random House.

Energy-conservation measures can be "sucker investments, and more sucker money is spent every day as people consider the next round of retrofits, to use that inelegant word for modifying a house to use less fuel," Rothchild writes. "I have friends who bought a woodstove, not realizing that the wood they burned was more expensive than the natural gas it replaced. . . . Many people have dutifully reinsulated their attics when the same money invested in other parts of the house could have produced double the return."

But poor investments can be avoided if homeowners have an idea of their houses' energy efficiency--learned, for example, from home energy analyses offered by local utilities--and if they investigate conservation measures before buying, Rothchild said in a recent interview in Washington.

The former Washington journalists, who now writes from his Miami Beach home, said homeowners' first energy and money-savings steps should be the cheapest. "Don't go for the big investment before you've tried all the little things'," he advised, "because the little things make the biggest savings cumulatively. Things such as plugging the air leaks in the house, such as wrapping the water heater with insulation, such as using flow-controller showerheads."

Rothchild's favorite and cheapest conservation device is a 10-cent water-flow controller, placed in a shower arm, that halves a shower's hot water use. But few stores apparently sell the plastic controller, which resembles a funnel, while the more expensive showerhead is widely available, he said. The controller is made by WF Products of Garland, Tex.

The controller is the first step in a four-part plan by Rothchild for families to slash their use of oil, gas or electricity to heat water. The other suggestions are to lower the water heater's temperature to 120 degrees if the family does not have a dishwasher, insulate the water heater, and wash clothes in cooler water.

Rothchild, who in 1977 was the co-author of a less detailed book on home energy, bases his latest book's recommendations on research done at federal and university laboratories--Lawrence Berkeley, Oak Ridge, Brookhaven and Princeton--and his friends' and, to a lesser extent, his own experiences.

"The more research the scientists did, the more they came to the conclusion that a lot of these little steps mentioned in the book were very, very important, and the installation of these various products was very important in terms of the quality of the installation," he said.

Rothchild learned firsthand the importance of correctly installing a solar water heater. Enthusiastic about taking advantage of the South Florida sun, Rothchild bought a solar system in 1978 for his former home in Everglade City. But his plumber incorrectly installed the device, causing about $800 worth of damage to the roof and unit. It took two more installers to get the heater working, but the electricity savings came to only about $800 worth of damage to the roof and unit. It took two more installers to get the water heater working, but the electricity savings came to only about $60 a year--about a fourth of what had been anticipated, he said.

The experience leads Rothchild to caution homeowners to thoroughly investigate solar systems and local contractors before buying a system. "'I don't think they're all bad," he said. "But it was a product that got so much positive publicity, and it couldn't deliver. Even at the Florida Solar Energy Center they seem to be fairly negative about it."

Homeowners can protect themselves from contractors' shoddy workmanship if they learn what the work involves, Rothchild said. "When the furnace person comes, you've got to know what a furnace efficiency check entails to make sure that's what you're getting," he said.

For insulation, he said, know the little details "that some contractors forget so that you can make sure that you get an adequate job, especially in wall insulation in house that has a lot of little nooks and crannies, bay windows, overhangs and things like that. Those are trickly places that have to be taken care of. And some contractors are very good about that and others aren't."

A key factor in increasing a home's energy efficiency is the furnace or boiler, with large savings often possible through modification or replacement of the equipment, Rothchild writes. He devotes a chapter to possible improvements for oil- or gas-burnng furnaces and boilers and electric heating systems.

With his tips comes a note of caution that switching from oil to gas "looks more and more like quite a gamble" because of possible soaring gas prices once the fuel is deregulated. But Rothchild says the new super-efficient "pulse combustion" furnace can make oil-to-gas conversion economical for some households, despite decontrol.