From the PSI analysis, it looks like your server is a big issue. Maybe it's time to change hosts?
Aside from that, it's just some unused CSS and render-blocking JS, which you can take care of easily. You may also want to see if you can reduce the size of your images, add caching, and Gzip.
For more information, input your site into these services:
https://tools.pingdom.com
https://gtmetrix.com