(FORTUNE Magazine) – Management genius Peter Drucker, who died on Nov. 11 at age 95, didn't admire "leadership" per se, remarking to FORTUNE, "The three greatest leaders of the 20th century were Hitler, Stalin, and Mao. If that's leadership, I want no part of it." But he had no problem telling you what it took to become a great manager. Below are edited excerpts from Drucker's article "The Effective Executive," which he adapted in 1967 from his book of the same name.

BUILD ON PEOPLE'S STRENGTHS

It is a characteristic of an effective executive that he builds on the strengths of his colleagues. To demand only well-rounded people, people who have only strengths and no weaknesses (whether the term used is the "whole man," the "mature personality," the "well-adjusted personality," or the "generalist"), is to invite mediocrity--of which there is always an abundant supply. There is far too little strength around for us to waste it.

KNOW YOUR MARKET

Effective executives make sure they go outside their own business to look, to listen, and to see for themselves. Recently a manufacturer of medical supplies found that it had slipped from a No. 1 position in its field to a poor second. "We have the same products," they told me. "In fact, ours tend to be superior technically." It turned out that the brash competitor had something else. Its top people had made it a point to spend many months a year away from their own organization--in hospitals, in doctor's offices, in operating rooms. They didn't go there to sell. They went there to observe and to listen. As a result they knew what the hospitals needed and in what form; medical men came to look on this company as the natural place to take their ideas.

CONTROL YOUR TIME

Certainly there is no such thing as an "effective type." Among the effective executives I have known, there are extroverts and aloof men, some even morbidly shy. Some are eccentrics, others painfully correct conformists. Some are fat and some are lean. Some drink quite heavily, others are total abstainers. Some are men of great charm and warmth, some have no more personality than a frozen mackerel. Yet it is also my observation that effective executives do have in common certain practices or habits--and practices can be learned. One obvious practice is the conservation of time. In a peculiar way the executive's time is everybody else's time but his own. Everybody can move in on him, and usually everybody does. He cannot shut himself off from these demands, but he must use the little time he can control to do the important things. This is the secret of those few people who accomplish so much with so little apparent effort. They put first things first.

PULL THE WEEDS

The problem is not just to get rid of programs and products that have obviously failed. The problem is to get rid of yesterday's successes that have outlived their potential. The effective executive periodically asks, "If we were not already doing this, would we go into it now?" Unless the answer is an unconditional yes, the chances are the activity should be dropped or sharply curtailed. The pressures are usually all the other way. It will be said in effect that "this product built the company, and it's our duty to maintain it and commit more resources." Most executives have learned that what one postpones one actually abandons. As a rule there is nothing less desirable than to take up a project today that one should have initiated yesterday. The timing is almost bound to be wrong, and timing is crucial in any effort. To do five years later what it would have been smart to do five years earlier is almost a sure recipe for frustration and failure.