Definitive "Must Do" For Wordpress LEMP Setup

As of about two weeks ago, I’m completely new to VPS, and came from shared hosting. I’ve learned quite a bit over the last few weeks, but I know there’s plenty more to learn. My simple question, what are the “must do” actions for a Wordpress website running on a LEMP setup? Here’s what I HAVE done:

-Installed LEMP -Installed Wordpress (site is up and running now) -Initial Security Setup (https://www.digitalocean.com/community/tutorials/initial-server-setup-with-ubuntu-14-04) -Created Sever Blocks for various websites -Configured SSH login for wordpress (https://www.digitalocean.com/community/tutorials/how-to-configure-secure-updates-and-installations-in-wordpress-on-ubuntu) -Configure SSH for Filezilla

That’s the gist of what I’ve learned / done thus far. A few things that need mentioning in my case:

My Wordpress installation is at /var/www/anightinburlington.com/public_html/wordpress and the site is served at . I tried to get help on the server block php config, but nobody seemed to know how to set it up. I blindly guessed and came up with this, which is the ONLY setup that’s worked thus far, but nobody has confirmed why / if this is right. Notice the root / try files setup:

root /var/www/anightinburlington.com/public_html;
	index index.php index.html index.htm;

	server_name anightinburlington.com www.anightinburlington.com;

	location / {
			# try_files $uri $uri/ =404;
			try_files $uri $uri/ /wordpress$uri/ /index.php?q=$uri&$args;
	}

The other thing, is that when I try to install W3 Total Cache, it says it can’t create directories, etc, etc, and everything I try seems to fail on that front (other plugins work fine, via SSH).

I’ve also looked into Memcache, but I’m not sure if that’s right for me, as I’m on a $5 droplet setup, with only 512MB of RAM. Can anyone let me know if there’s anything else I should do before I’m essentially good to go? Any information on my other questions would be great as well - many thanks!