1. Routinely review search terms to filter irrelevant traffic generated from Google's liberal broad and phrase matching algorithms.
2. Run automated scripts to identify and filter fraudulent publishers on Google's display network.
3. Use offline conversion metrics to identify and eliminate sources of low retention/high refund customers.
4. Optimize your landing pages for mobile traffic, including page load speed. (In most markets, the majority of traffic is from mobile users.)
5. Review KPIs from mobile app traffic channels. In most cases, exclude all app traffic.