If 1982 was a year for interest-rate investments, 1983 is shaping up as the year small investors returned to stocks. New sales of mutual funds that invest in stocks reached a record $1.6 billion in January, and a near-record $1.5 billion in February.

Trading volume is up sharply on the American Stock Exchange and in over-the-counter issues, reflecting the small investor's surging interest in lower-priced stocks. Stockbrokers are reporting a boom in new accounts.

On Wall Street everybody has a theory. The most popular theory has it that we're now approaching the second phase of a typical, three-phase market rally.

Bull markets always start with an interest-rate rally, when rates fall and professional investors start to switch their money out of Treasury bills and money-market mutual funds and into stocks. The interest-rate rally for this particular market cycle started last August and was unusually robust. The rising tide lifted almost all stocks.

But falling interest rates can only ignite a rally; they can't keep it going. To supply a bull market with staying power, corporate earnings have to rise. That's the second phase of a bull market--the earnings rally--locking into an improving economy. Economist S Jay Levy, a specialist in profits forecasting, sees a sharp increase for profits in 1983.

There is usually (but not always) a brief decline between the interest-rate rally and the earnings rally. If today's market follows the shape of the big market rises of 1970 and 1974, says Yale Hirsch, publisher of the newsletter Smart Money, the Dow Jones Industrial Average should be topping out around now and will drop by 12 to 17 percent over the summer.

"Chances are that the real pain will be inflicted in May or June, a disaster area for stocks in 15 of the past 18 years," Hirsch says. He predicts a drop from the present 1,170 area on the Dow industrials average to around 1,000 or 1,050, followed by an earnings rally that will carry the stock-market average to around 1,400 over the following year--and maybe even higher, he says, if Republicans are reelected.

An earnings rally doesn't boost all stocks. The better companies far outshine the pack. Analysts look for real gains in profits, which Levy describes as "increasing sales, while holding down costs." (Profits arising from depreciation or from the increased value of goods in inventories Levy describes as "spurious profits.")

Among Levy's industry forecasts: Defense--coming in for a rising share of corporate profits. Housing materials and residential construction--a particularly strong improvement as the year progresses. Major appliances and furniture--helped by lower interest rates. American-made autos--the best year for sales since 1979. Steel--improving with the auto and appliance market. Airlines and chemicals--helped by lower oil prices.

David Dreman, author of "The New Contrarian Investment Strategy," urges investors to concentrate on big, strong companies that are temporarily out of favor in the market. Study after study, he says, shows that their stocks go up the most. Dreman looks for companies with a low price-earnings ratio, high and increasing dividends and a solid record of earnings growth over the past five to 10 years.

Right now he likes insurance companies, oil companies, food companies and supermarkets. The popular high-technology stocks are too highly priced for his taste, and too vulnerable to market turns.

Perhaps the most effective way for the small investor to buy stocks is through a stock-owning mutual fund. The United Mutual Fund Selector recently put 571 mutual funds through a stringent performance test; of the top 75 funds of the past year, only 32 did equally well over the past three-year and five-year periods.

First on the list: Fidelity Magellan (from Boston's Fidelity group); next came four gold funds--Strategic Investments, United Services Gold Shares, International Investors and Research Capital; then came IDS Growth, American General Pace, NEL Growth, Hartwell Leverage and Loomis-Sayles Capital Development.

The top 32 funds rose 54.2 percent in the 12 months ending Feb. 2, compared with 33 percent for all funds and 26.4 percent for a similar stretch on Standard & Poor's 500-stock average.

I did not, by the way, forget about the third phase of the typical bull market. It's the fizzy, speculative phase, not yet in view. After the fizz, of course, comes the fall--not likely, the analysts say, until after election-year 1984.