1. Have a Negative Keywords List
Use negative keywords so that your ad does not appear for search terms that are not relevant to you.
2. Pay Attention to Quality Score
Higher Quality Score gives you higher ranking with lower cost
3. Separate / Create Keyword Buckets for Each AdGroup
You can ensure that the text in every ads explicitly relates to the term searched.
Identify the countries which are particularly important to your company. Build your ads and target to these countries.
5. Target on Conversion
You should target on conversion and not click-through rate.
Try to keep conversion numbers up and conversion costs down.
6. Track Your Account Performance by analyze statistics data
Using Google Analytics on your website. It helps you measure your ad performance and provides different performance indicator.
7. Create Multiple AdCopies and perform A/B test
Continual modifications will be required to ensure success.
Pay-Per-Click advertisement is a test and change iterative process.
You should keep revising your ad and see if the changes work.