There are certain recommendations from Google Page Insight Speed reports that are not possible to be handled from code (and this applies for any website that offers you services like Google Maps, IDX support and so on).
– while you have a theme with third party JS (Rev Slider, Google Maps)
Also consider that you have plugins that each comes with their own js/ css files.
Minify is a process that basically encodes files. Theme files can be minified from theme options – help http://help.wpresidence.net/2016/03/03/wpresidence-theme-options-minify-css-and-js-file/
External resources about minify –https://developers.google.com/speed/docs/insights/MinifyResources
Enable caching for third party – Google Maps – is not possible because google doesn’t allow it.
Optimize images is something each person does as images are added by each client. Gimp desktop app is a tool to optimize images (for example)
On items like Remove query strings from static resources- there’s nothing to do since the variable detected is the script version from wp. And it will gain no actual speed
For the server you have 2 important things you can do
Specify a Vary: Accept-Encoding header
Enable gzip compression
on Minimize redirects
If you are using 2 tpes of url – with www and without www. Use only the one with www
Use a cache plugin like wp-fastest-cache – besides cache it also does mimify js and css