As well as wanting to regularly check for updates so any security vulnerabilities are patched, you should also check for updates before installing anything new as often applications rely on the system being up to date to be able to install correctly.
Updating all installed packages
sudo apt-get update sudo apt-get upgrade
sudo apt-get update; sudo apt-get upgrade
Automatic Updates, Upgrade, Remove unused, Remove old
This updates the packages, upgrades the packages, removes unused packages, then removes old versions of packages.
sudo apt-get update -y && sudo apt-get upgrade -y && sudo apt-get autoremove -y && sudo apt-get autoclean -y