These are only a couple of points. You could add so much to it... srcset, http/2, minification etc.

Saying that, why create the post at all? I don't mean that in a harsh way, I mean to say that if you are testing with google page speed, it tells you exactly what you can improve on and how to do it!

I recommend to use Crunch for PNG compression. The result is so impressive I don't see myself using JPG again.

https://github.com/chrissimpkins/Crunch

What so many of those optimization guides really miss is that it is also about making content choices. If your visual direction is going to be image heavy, let alone video, or you have long pages with much varied content, that level of optimization is often not your main concern in a quest to get better load performance.