This is Part 2 of a 10-part series on 10 things we believe about search marketing. These 10 beliefs form our product design philosophy .
We firmly believe that the best source of keyword data is your own customers. Too often, search marketers over-rely on third-party keyword suggestion tools  and neglect their own website data (server log files and keyword analytics), a completely private, self-renewing source of keyword data.
Keyword suggestion tools are fine as a jumping-off point for keyword research , but then you need to go beyond that. Build on public keyword data by refactoring insights from private data into your list for an extensive, expanding keyword research database . We believe your own website data has a number of advantages over typical keyword tools:
Personalized keyword research based on real data empowers you to make more strategic search marketing decisions. Your content for both organic and paid search  campaigns is more relevant, better targeted to your audience and achieves higher keyword rankings  (in the case of PPC, for lower costs).
At WordStream, our keyword research efforts are ongoing and always incorporate this invaluable private data from our customers and readers.