Don’t flatter. Sincerity in business is as commendable as sincerity in religion.
Don’t “put on” a civility and formal politeness which are not natural to you.
Don’t trust to persuasion alone to land your prospect. Convince him. Persuasion is the soft glove; conviction is the iron hand underneath. Let your manner be as conciliatory as possible, but put into your arguments a firm grip of conviction that he cannot get away from.
Don’t dodge a question or objection. Answer it fairly and squarely.
Don’t assume to know more about his business than he himself does. Even if you do, you can’t make him believe it.