The Law of Athens

When asking for help, appeal to people's self-interest, never to their mercy or gratitude. In 433 D.C., just before the Peloponnesian War, the island of Coursera and the Greek city-state of Corinth stood on the brink of conflict. If you need to turn to an ally for help, do not remind him of your past assistance and good deeds. He will find a way to ignore you. Instead, uncover something in your request that will benefit him and emphasize it out of all proportion.