The people to keep on side can vary: in a democracy, leaders need to worry about who's important in their context.

That means above all understanding your audience and targeting your speech.

Choosing good and independent subordinates and listening to them is a safeguard against making bad decisions.

Often leaders have chosen to stay on when they should have bowed out. Without intending to, they often undo much of their own work and cause problems for their successors.

Leading can be gratifying but also lonely. Ambition and the determination to succeed may mean sacrificing friends and family.

A job can subtly warp your judgement so that you only see things from one perspective.

Mustafa Kemal Ataturk, the father of modern Turkey, accounted for his limitations by issuing an order to ignore instructions he gave in the evenings – when he liked to carouse with his friends. But history has far more examples of leaders whose convictions of infallibility grow in proportion t...