Help with YSlow Speed

Hello, I’m a web designer and I am always using WordPress themes. I’m learning more how to optimize my site better through GTmetrix – awesome site has helped me a lot to learn how to configure my .htaccess file. However, I am still struggling with the Yslow speed.

See Here: https://demo.kjrinteriordesign.com/wp-content/uploads/2015/08/Screen-Shot-2015-08-14-at-1.13.36-PM.png

I have no idea how to get these score higher, I’m lost. Any help would be appreciated, Thank you!