Automatically Upgrade Kali, Ubuntu, or Debian via Cron and Apt-Get

In order to automatically upgrade packages on a Kali, Ubuntu, or Debian system, I add the following line to my crontab as root:
sudo crontab -e # To edit the root user's crontab
Then add this line to run the updates at 8:00AM:
00 8 * * * /usr/bin/apt-get update > /dev/null 2>&1 && /usr/bin/apt-get -y dist-upgrade > /dev/null 2>&1 && /usr/bin/apt-get -y autoremove > /dev/null 2>&1

Optimizing Kali, Ubuntu, or Debian Linux By Disabling Services That are not Required on Boot

Services that are started on boot in Kali Rolling, Ubuntu, or Debian can be removed with the tool rcconf.
To install rcconf, use apt-get:
apt-get install rcconf

Services that start on boot that can be disabled are:
arpwatch (if you aren't looking for people arp poisoning you)
clamav-daemon
clamav-freshclam
gdm3 (if you don't use Gnome)
gdomap
lightdm (if you boot straight to console)
motd
pcscd (if you don't need smart card support)
pppd-dns
rsync
saned (if you don't use a scanner)
smartmontools (if you don't need to monitor your hard drive health)
speech-dispatcher
x11-common (if you boot straight to console)

If after restarting and rcconf still shows a service you removed, then you can force the disabling by issuing the command:
update-rc.d -f service_name remove

Enable SSH Server on Boot in Kali Linux Rolling

To enable the openssh server to start on every boot in Kali Linux Rolling run the following command:
update-rc.d -f ssh enable 2 3 4 5