Here are some good PPC tips from RevenueWire
A Great Way to Find Negative Keywords
"How do many affiliates discover negative keywords? Often times it’s the ‘imagination method’, trying to personally imagine what danger zone keywords could apply to a niche campaign. More often than not however, it’s only after looking at search query and content placement reports that affiliates discover the number of probable negatives that have been costing them dearly in irrelevant clicks."
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