The single most important thing any family can do to fight inflation, says Susan Kelliher Ungaro, is budget.

"But many people are turned off at the prospect of budgeting," notes Ungaro, a senior editor specializing in money and consumer topics at "Family Circle" magazine.

"The word has a negative connotation. It sounds too much like scrimping along. So even though today's families are finding it incredible difficult to manage their money and stay out of debt, many resist budgeting.

"And there are a lot of myths about budgets -- that they're just for low-income families, or require complicated math skills, or are just a waste of time."

But for inflation-shocked families, where "pocketbook pressures have made money the No. 1 cause of family arguments," says Ungaro, "budgeting is the only answer.

"About 70 percent of a family's income today goes to pay for necessities such as housing, health care, food and clothing. To be able to still have money left over for luxuries like movies, dinner out, a vacation -- which most people consider necessities -- most families must economize, sacrifice and budget. Or else use credit to the limit.

"Misues of credit is one of the major causes of financial disaster. And most people don't take money management seriously until they are in financial trouble. But a budget is a sensible, well-thought-out guideline to the family's spending power that can put everything into perspective and prevent disaster."

Ungaro calls her book of budget worksheets, credit guidelines and money-saving tips "The H & R Block Family Financial Planning Workbook" (Collier Books, $4.95).

"Financial planning has a more positive ring as an approach to a family's money management," says Ungaro. "It involes sitting down, making plans and setting goals."

The two biggest mistakes families make about money, she says, are the way they view their income and use their credit -- both of which add up to living beyond their means.

"People tend to live and think in terms of their gross, before-tax income. They figure 'We make $30,000 a year so we should be able to afford such and such.' They seem to close their eyes to the fact that, after taxes, they may bring home more like $22,000."

This problem is particularly severe for dual-income couples, she claims.

"One bank reported that two-paycheck families run a higher risk of falling into debt than one-paycheck families, because along with increased spending power can come a false sense of financial security.

"Many people fail to consider the hidden expenses that accompany two incomes -- child care, work clothes, transportation, lunches. If you don't budget your money, these may get overlooked."

Credit misuse is the other big money mistake.

Says Ungaro: "Inflation has Americans running scared . . . and fighting back the only way they know how -- buying now while the prices are still 'low.'

"It's so easy to charge everything from doctor bills to a college tuition. Many people would think twice about paying $70 for a blouse if they had to plunk down $70 cash. But plastic makes it painless. No wonder a debt of almost $5,000 is owed for every person in this country."

Confirmed credit-card junkies, she says, can change their spendthrift habits by "keeping a record of every credit-card purchase -- the way you keep track of each check you write.

"And stop treating your credit card like a status symbol. Pay cash if you've got it, or use a check -- at least that way you won't be borrowing. If you feel you must charge something, ask yourself if you would still buy the item if you had to hand over the cash."

While each family should figure out their own system for handing finances, "Both partners should know where the money goes. Try to take a positive approach to sitting down together and working out the budget. Don't pick a time when you're rushed, because your chances of error then will be greater.

"There are ways to share the burden -- the better correspondent can pay the bills, the one who's better with figures can balance the checkbook."

It's also important says Ungaro, to let children know about a family budget.

"If money is treated as a private, hush-hush topic, how are kids going to learn to be a good money mangers and smart consumers? Plus, parents who involve their children in money discussions have fewer fights with their youngsters about money."

Although one-third of American families have no savings account, and "a majority save irregularly, if at all," Ungaro says, "One of the most important aspects of financial planning is saving.

"Financial advisers often recommend investing 10 percent of your income in savings of some sort -- a savings account, stocks, bonds. But only you can decide how much you can afford to save.

"But even a little adds up.Just $25 a week equals $1,300 in a year -- plus interest. It gives you a sense of accomplishment to see the balance going up -- and a feeling of control. Saving is a way of taking control of your life. And in times like these, that can be a big help."