We run Google Analytics behind all of our PPC landing pages to learn more about what’s going on than we can see with Google AdWords reports.
I stumbled upon a handy script from ROI Revolution that you can add to your GA code to show you exactly which keywords and keyword phrases people are typing into Google that lead them to your landing page.
“Here’s an example: you’ve got a shoe store and you’re running Broad Match AdWords ads for “shoes”. When a visitor searches Google for “blue suede shoes”, your ad shows up. This is all well and good, but what if you don’t sell blue suede shoes?”
After the script is in place on your landing page, you’ll find the report in Google Analytics under Visitors > User Defined.
Run the report and see which keywords people are using and find those that don’t apply to your landing page and add them as negative keywords to your Google AdWords campaign. You might also want to sort the report by bounce rate and see if any keywords or phrases with 100% bounce rate should be added as negative keywords as well.