nginx-ssl-config.conf

       ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
       ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;
	 
       ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
       ssl_prefer_server_ciphers on;
       ssl_ciphers "EECDH+AESGCM:EDH+AESGCM:ECDHE-RSA-AES128-GCM-SHA256:AES256+EECDH:DHE-RSA-AES128-GCM-SHA256:AES256+EDH:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA:ECDHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES128-SHA256:DHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES256-GCM-SHA384:AES128-GCM-SHA256:AES256-SHA256:AES128-SHA256:AES256-SHA:AES128-SHA:DES-CBC3-SHA:HIGH:!aNULL:!eNULL:!EXPORT:!DES:!MD5:!PSK:!RC4";
       ssl_session_cache shared:SSL:10m;
       ssl_dhparam /etc/ssl/certs/dhparam.pem;
       ssl_session_timeout 1d;
       ssl_session_tickets off;
       ssl_stapling on;
       ssl_stapling_verify on;

       add_header X-Frame-Options DENY;
       add_header Strict-Transport-Security max-age=15768000;
       add_header X-Xss-Protection "1; mode=block";
       add_header X-Content-Type-Options nosniff;
       
       location ~ /.well-known { allow all; }

To renew the certificate:

letsencrypt-auto certonly -a webroot --agree-tos --renew-by-default --webroot-path=/var/www/example.com/public -d example.com

to generate dhparams.pem

cd /etc/ssl/certs
openssl dhparam -out dhparam.pem 4096

(takes a long time)

Then add your website to https://sslcatch.com which is going to send you an email 60days before the expiration, just in case your crontab does not work.