Keep in mind that historical keyword performance is an important factor in determining which keywords are worthwhile. Google maintains statistics on the performance of keywords historically, which includes all other campaigns besides your own that target those keywords. If certain keywords have failed to attract ad clicks historically, then Google downgrades those keywords and you might have a difficult time getting a good keyword quality score no matter how relevant those keywords are to your ads and landing page. Poor performing keywords are typically keywords that don’t pertain to marketable products or services or are just too general. Always choose specific keywords that pertain to your products and services.
Excerpt from: Don’t Waste Money on Google Adwords
The best keywords for Google AdWords are keywords that are most relevant to the products or services featured in your Google ad. You should include all popular variations of those keywords to match the multitude of ways people search for your products or services, including slang, idioms, colloquialisms and alternate grammar.
First and foremost, the best keywords to trigger your ads are keywords which are as relevant as possible to your ads and your website landing page. The reason being, Google will assign your keywords a quality score, which is based upon the relevance of your keywords. Your quality score goes a long way to determine how often your ads get placement and how much you will be charged.
To find the best keywords for your ad campaigns, start with the specific product or service you are offering. You can then use the Google Keyword Tool to help you search for variations on that product or service which you can use as your own keywords. The Google Keyword Tool will show you not only dozens of variations on your keywords, but also how often each keyword gets searched. Naturally, you’ll want to choose relevant keywords that are commonly searched. Make sure you consider the various ways someone might be searching your product or service, including slang, idioms, colloquialisms and alternate grammar.
As an example, imagine you are advertising services for Google AdWords copywriting. Here are some examples of which keywords you might choose for your ads: “Google AdWords copywriting,” “AdWords copywriting,” “copywriting for AdWords,” “AdWords expert,” “AdWords specialist,” “Help with AdWords,” “AdWords copywriter,” “AdWords writer,” “Writer for AdWords,” etc.
To learn more about how to choose the best keywords for your Google AdWords campaign, read Don’t Waste Money on Google AdWords.