Use your advertiser account's Tracking and Reports feature regularly to monitor your ad's performance. Views, click-throughs, cost, and average rank data can indicate where opportunities lie to optimize your ad's effectiveness.
Before making changes to an existing ad, review and record its performance using Tracking and Reports. After you make changes, go back to Tracking and Reports to see if and in what ways these changes improved results. This will help you develop strategies for optimizing your ad.