Using LetsEncrypt for SSL/TLS
See LetsEncrypt for more information.
Create the certificates (use your domain names)
certbot certonly --webroot -w /mnt/www/letsEncrypt/ -d example.com -d www.example.com -d thing.example.com
Update NGINX config
nano /etc/nginx/nginx.conf
# un-comment the SSL listen line
listen 443 ssl http2;
# un-comment and edit the SSL certificate lines
ssl_certificate /etc/letsencrypt/live/example.com/chain.pem;
ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;
add_header Strict-Transport-Security "max-age=31536000; includeSubDomains";
Reload NGINX
/etc/init.d/nginx reload