Perception is the key as to why a customer shops and ultimately purchases your product or service, or why they don't. Take Volvo for example, they have done a terrific job of creating the perception of safety for their vehicles. If you want to drive a "safe" car, you'll shop their brand. On the flip side, if you want a fast, sporty car, you'll shop Porsche instead.
What a local advertising agency can do, is work with you to find out what perception you want potential customers to have about your particular product or service. Determine your best possible way to place that message in their minds, and keep the message consistent. We keep you true to the message during the times that you feel it's run it's course, because by the time you're tired of the message, your potential customer is just beginning to notice it...let alone figuring out if it affects them in some way.