Stock markets will careen from heights of Greed to pits of Fear and back up again, unto the last syllable of recorded time. Today, with the Greedometer riding high, Wall Street is rubbing its fattened hands over the prospect of a boom year in new issues, which pull in money like a magnet.

New issues are the stocks of companies going public for the first time. So hot is the market that about one-third of the companies that filed in January to go public aren't real companies at all. They're blind pools, which means that they'll take your money and then look for something to invest in.

The question is, do you really want to take the ride?

One reason to say yes is called Liz Claiborne Inc. Since its debut in 1981, the company has showered its lucky investors with a return on their money of more than 1,200 percent.

But then there's Diasonics, the very embodiment of why you might say no.

Diasonics was one of the biggest and hottest new issues of 1983. I remember that none of the brokers selling the stock even seemed to know what the company did. All that mattered was that Diasonics shot 6.1 million shares out of the starting gate at $22 a share and, in the blur of first-day trading, reached $26.75.

But doubts set in almost immediately. By the end of last year, it had lost 85 percent of its opening value.

In a recent study of 1,922 new issues that came out in the past decade at $1 or more a share, Forbes magazine concluded that the deck was stacked against investors. At the end of last year, roughly six out of every 10 new issues were selling for less than their offering price. About one in 25 wound up in bankruptcy. About one in eight was almost wiped out.

But looking at 1985 alone, the picture looks a little brighter -- by which I mean that more than half have risen above their offering price.

Companies are always going public, in good markets and bad. And they follow a cycle to which investors should pay more attention.

The start of the cycle is dominated by companies with good earnings that have been in business for four or five years. They are often excellent buys.

But as speculation heats up, you start to see copycat companies -- modeled on earlier, successful issues but with poorer track records. Next come companies that are losing money, or haven't even gone into business yet.

Any one of these stocks can soar for a while, if the market is running. But large numbers of them eventually will go down the tubes. Some tips on buying smart:

* Forbes found that the brokerage houses with the best records for producing stock-market winners were the medium-size, regional houses that concentrate on local companies and know them well. The brokers at the top of the list: William Blair & Co., Chicago; McDonald & Co., Cleveland; Wheat, First Securities, Richmond; A. G. Edwards & Sons, St. Louis; and Robinson-Humphrey of Atlanta (owned by ShearsonAmerican Express). Investors interested in new issues might want to open accounts at these firms.

Of the bigger firms, Forbes took notice of Salomon Brothers, Goldman, Sachs and E. F. Hutton.

* Of the national new-issues specialists, Norman Fosback, publisher of the New Issues newsletter, told my associate Virginia Wilson that he'd choose Alex. Brown & Sons (which has itself gone public), L. F. Rothschild, Unterberg, Towbin (now going public and recommended by Fosback as a buy) and Robertson, Colman & Stephens. All ranked lower on Forbes' list.

* As a strategy, Fosback suggests that, if you can't buy at the offering price, wait until the stock has been out for a while. Then try to buy it on the open market for less. By one count, about two-thirds of the new issues eventually drop below their opening price. Don't chase the prices of these stocks up, he warns. If the company gets away from you, just wait for another offering to come along.

* To get a shot at the good new issues on their opening day, you will have to work with a broker who sells a lot of them. And he may require you to buy some of the bad ones, along with the good. That's where investors often lose. Their losses on the cats and dogs overcome their gains on the occasional winners.

* Don't buy when a good part of the stock being sold to the public comes from the company's insiders. If the people who founded the business are selling out, they probably have good reason to. And that's reason enough for you to stay away.