Never stop testing, and your advertising will never stop improving. Testing was used in advertising decades ago. The internet has made testing so easy that every online marketer can use it to improve advertising results. Google content experiment is a free tool for you to do split testing.
David OgilvyHire people who are better than you are, then leave them to get on with it. Look for people who will aim for the remarkable, who will not settle for the routine.
David Ogilvy