NEW YORK (AP) _ Some of your smartest, best educated friends never catch on to the rules of the game, says Allen Cymrot. ''They live in a capitalist society, but they never learn to live as capitalists.''

Instead, he states, they live under constant financial stress, forever frustrated by their inability to improve the quality of their lives. And all because they do not know the name or rules of the game.

''When you're on the football field you play football,'' says Cymrot. ''And in a capitalist society you should seek to live like a capitalist.''

In his view, you should consider yourself a business, with a balance sheet and profit-loss statement. You must understand net worth, because it is that, rather than current income, he contends, that raises the quality of life.

Cymrot learned the lessons a long time ago, practiced them as an executive responsible for buying and selling more than $1 billion worth of property, and now, as a labor of love, wants to teach the lessons.

He has written a book, ''every evening at home for a year on a yellow pad or personal computer,'' to help preach his philosophy that ''a person is as responsible for personal wealth as surely as for personal health.''

He calls it ''Street Smart Real Estate Investing,'' but it is more than that. It is a strategy for increasing net worth and the key to a high quality material life, a message that sounds simple but is forever overlooked.

Because he is a real estate person, he uses real estate to illustrate his concept - that the mass of people live lives of quiet desperation because they try to finance everything on current income rather than business investments.

No matter how well educated, Cymrot laments, people make the mistake. But, he says, 99 percent of the academic curricula that tell how to make money offer nothing on what to do with it.''

And what do most people do with it? They use it, but never really invest it.

''They live like socialists in a capitalist country. They don't know how to generate net worth, so when they run into trouble, when they seek to raise the quality of their lives, they want government to legislate wealth for them.''

The theme of Cymrot's book, published by Dow Jones Irwin, is this:

You must develop a profit and loss statement. Any excess earnings from the P&L statement should go into good investments. Those investments move tangible assets to your balance sheet. As these investments grow, net worth increases.

When you seek to buy a home, a car, a boat or finance your child's education, the money comes from your balance sheet - your net worth - not from your current earnings.

''These expenditures are financed by the strength of your balance sheet. Your income may make the monthly payments, but your balance sheet provides funds for the down payment,'' he says.

He stresses the idea in the book: ''Income buys daily necessities and little frills; ASSETS BUY OTHER ASSETS.''

Cymrot knows his subject, and practices it. He is chairman and director of the National Multi-Housing Council, and former president and director of Robert A. McNeil Corp., one of the country's largest real estate entities.

Now chief executive officer of Woodmont Realty Advisors Inc. of Belmont, Calif., a company that invests in properties for pension funds, he continues to build his personal net worth through outside investment activities.

It is from experiences with both individual and executive investing that he draws the material for his book. But the concept does not depend on real estate, although Cymrot believes it is a superior vehicle. Any good investment will do.

In his meetings with investors and students - he lectures frequently to graduate students - he says he has found all human beings have some aspect of success - in business, social life or through charitable involvements.

''But the vast majority of people haven't carried that success into their investment life,'' he says in the book. ''There seems to be a bridge that is missing.''

He hopes this book can be that bridge, ''connecting those principles that reflect your success in other aspects of your life with the investment side of your life.''

End Adv PMs Wed July 27