If you plan to make changes to your account, but are not sure how to analyze impact and would like to make sure that the differences are actually significant, you can take advantage of AdWords experiments.
Decide what you'd like to change and measure. Here are a few ideas:
Create new ad variations to run against current ad text. You can experiment with using special offers, discounts versus price points, different calls-to-action, extra words in your Display URL, and many other ad elements.
Make changes to ad group or keyword bids. You can start with ad groups that are losing impression share due to ad rank.
Add new keywords to existing ad groups. Focus on ad groups that are not getting enough traffic.
Add new ad groups to an existing campaign. Try new categories or match types.
Keep in your mind your goal metrics that are important to your business, such as conversions.