We are convinced by advertising based on consistency and coherence, not the quality and quantity of information.
The best ad campaigns involve a simple clear emotionally evocative idea repeated over and over again.
Less is in fact more.
You can’t just sit down and write good copy all day long. I surround myself with books, and make myself choose one of these, open it up, and find a word at random, which I then force myself to include in a sentence – it helps me get into the flow of writing again.