Please find below steps to increase Google Page speed  insights…

1. Add w3 total cache plugin within wordpress site.
2. Activate page cache, browser cache, database cache etc… in w3 cache plugin.
3. Optimize images with wordpress using WP Smush Plugin or with the help of designer.
4. Install “Google Pagespeed Insights” plugin to check page by page performance.
5. Install “Autoptimize” plugin and set CSS & JS optimization.
6. Finally insstall WP Performance Score Booster to increase page speed insights.

Now website max  Page Speed Insights more than 86 for desktop and more than 70 for mobile.