Savers and investors need an extra dose of foresight as they try to plan how to manage their money in 1989.

In addition to the usual imponderables - the likely direction of the economy, interest rates and stock prices - they are faced with the first change of occupancy at the White House in eight years.President-elect George Bush and a Democratic Congress are under mounting pressure to shrink the federal budget deficit. The decisions they make, or don't make, are likely to influence the outlook for investments of many kinds.

"Expert" opinion isn't much help in sorting out prospects for the new year. A sampling of about a dozen financial forecasts for 1989 yields these conclusions:

The economy either will, or will not, slip into recession. Interest rates probably will come down if the economy slows, but they may rise further before the decline starts. And the stock market - well, it will fluctuate.

But there still are ways to plot a reasonable plan of action, based on what is known now and on educated guesses you can make about the future.

The unusual pattern of interest rates that prevails as 1988 draws to a close makes some income-producing investments look appealing and others chancy.

Rates on many relatively short-term investments, with lives of two to 10 years or so, are now as high as, or higher than, what you can get with a longer-term commitment.

For example, as of mid-December 30-year Treasury bonds were yielding 9.02 percent, while three-year Treasury notes offered a 9.17 percent yield.

In these circumstances, known to investment professionals as an "inverted yield curve," there isn't much incentive to take the extra risks involved with a long maturity.

Or consider a five-year certificate of deposit yielding somewhere around 10.29 percent - the national average at banks and savings institutions reported by Bank Rate Monitor as of Dec. 7.

Like Treasury securities, CDs are available with the backing of the federal government, in the form of deposit insurance.

There's no overlooking the much-publicized threat to the deposit insurance system of insolvent savings institutions, with an unpaid bill that grows larger by the day.

Among the government's possible options in dealing with this problem, however, reneging on its promise to depositors does not seem workable, even if someone thought it was a desirable choice. Discrediting deposit insurance would likely create havoc in all the markets.

If you are convinced that interest rates are headed higher in early 1989, a logical choice would be to keep your nest egg in a money-market investment with a very short maturity.

The average yield of money-market mutual funds, as reported by Donoghue's Moneyletter of Holliston, Mass., recently stood at 7.75 percent. It would quickly move up further if short-term rates continue their recent rise.

The newsletter's current view: "Long-term bond funds are not attractive now compared to money funds or even short-term bond funds. Investors just are not being paid to be in more volatile long-term bond funds.

"We think the time for a switch to long-term bond funds will come, but it hasn't yet."

Prospects for stocks and stock mutual funds continue to confound a lot of very sharp minds. Many experienced investors have been waiting since early in 1988 for a market decline and a recession to make stocks available at bargain prices.

So far the market has refused to accommodate them.

As Thomas Bailey, chairman of the Janus Group of mutual funds, put it in a recent note to shareholders, "Today's stock market is `okay.' But it does not represent any real bargain."