PPC Primer is written by web developer and search marketer 
AdWords tip: Use negative keywords
Negative keywords cause an ad to not be shown if any of the keywords are in the search phrase. Using negative keywords ensures that your ad is only displayed for relevant searches, increasing your CTR and eventually lowering your bid costs.
When setting up negative keywords for your AdWords campaigns, only place one negative keyword per line and precede each keyword with a dash.
Are you using negative keywords yet?
