When advertising, it is imperative to test the results of a particular campaign and adjust to the results. An advertising campaign, whether on the internet or in print can be quite expensive if the outcome is ineffective. For this reason, testing individual campaigns can be of the utmost importance. In newspaper advertising, for example, a print ad should be tested over a 3 week period to determine overall effectiveness of an ad. All ads should be repeated and tested over a set amount of time then results need be evaluated and the ad should be modified accordingly.
This process of repetition and testing is a process that had worked through the ages. Think of your favorite song for a moment, a majority of the words you will remember is the chorus. The repetition is what triggers memory retention. Also known as "The Hook" ( for good reason ); it is the first part of any song that is remembered. Like in music, good advertisements have a repetition usaully referred as a headline. Use the headline and variations of the headline throughout the ad, preferably three times.
Follow these rules and get on your way to writing better copy.