To improve advertising, the response should be tested regularly. Look at the results in terms of orders and inquiries, when the campaign is started.
See what happens if the advertisement is moved to different slots, if the size or wording is changed, if a different medium is chosen.
It may be worth dropping the campaign for a month or two especially with press advertising which loses effectiveness the longer it is run.
Evaluate the optimum cost benefit ratio for the length of a campaign. Then introduce a new campaign after, say three months. The next time try a ten-week break and compare the results.
By constantly looking at results, it should be possible to evaluate the best spot in the best media, the most effective size of advertisement, the style of copy, the length of the campaign and the frequency of the campaign.
When using coupons, add a code for each advertisement if the campaign uses more than one piece of copy. Also ask customers how they heard about the company and what they thought of the advertising. An objective, third party view can be valuable.