Don't cannibalize your natural rankings with expensive paid search ads. There is an interaction between natural search entries and paid ads. Say you rank organically in Google for the term "Stop smoking ad" and you also have paid ads competing on the same search results page. The paid clicks you purchase might be clicks you could have had already. It's a judgment call. Are the clicks 20 cents or 10 dollars? And, even if you do pay for some of your traffic, are you earning a positive return on investment in the paid click channel?
Perhaps the most egregious example of the cannibalization of organic traffic is the purchased paid clicks for one's own business name. This practice almost certainly directs users into paid clicks when the organic entry is clearly visible. National brands often employ this technique. Brands such as Dr. Pepper and Federal Express purchase paid clicks in the Google Adwords program. This practice is almost never necessary...