Step 1: Ensure Goals and E-commerce Tracking are set up
Step 3: Export non-paid keywords to a spreadsheet
Step 4: Expand the list of keywords using other Google products
Step 5: Download a list of keywords that you are already advertising on
Step 6: Identify keywords you are not advertising on
Step 7: Expand on these keywords and start advertising
For explicit directions on each of these steps, take a read of the article. You and your website will benefit. Of special note - step 4, which we've pasted in below. As you can see, Vinoaj, the author, gives you an extensive list of Google products that can help you refine or expand your keyword list. Some of them you've probably never even heard about, but will simply take your targeting to the new levels, especially when budgets are tight but you want to grow your business as Q4 approaches.
To consider more keyword options, consider using some of Google's other free products to discover more opportunities: Google Insights for Search, Google Trends, Site Search reportsin Google Analytics, Webmaster Tools, and even the new Wonder Wheel. If you are an AdWords user take a look at the Keyword Tool, Search-based Keyword Tool, Search Query Performance reports, and more. Once you have identified additional keywords you would like to advertise on, add it to your list of keywords from Step 3.
Happy analyzing!