In the (relatively) new Google AdWords interface, there is a new tab called Opportunities, in here Google will periodically offer you campaign optimization tips.
The best idea is to go and review these suggestions on a monthly basis as these tips are constantly changing based on consumer search behavior and patterns.
On the left side, you can select a campaign the same as you would in the Campaigns tab. When you select a campaign it will show you a list of ad groups with suggestions. Click on each ad group and you will see a list of search terms that Google suggests you add to the ad group. You should always review before accepting because they will suggest many keywords that may be to generalized for your campaigns success.
By doing this monthly, you will keep growing your campaign target audience based on Google’s historical data and metrics.
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