To update a system using a locally attached keyboard and screen do:

sudo apt update

sudo apt full-upgrade

sudo apt-get autoremove

sudo apt autoclean

Or all in one the old way:

sudo apt-get update && sudo apt-get upgrade -y && sudo apt-get autoremove && sudo apt-get autoclean

all in one, the modern way:

sudo apt update && sudo apt full-upgrade -y && sudo apt autoremove -y && sudo apt clean

cat /var/log/apt/history.log shows when last update has been done

sudo shutdown before removing power would be the clean way

sudo df -T to check memory size of the SD card

sudo apt-get clean do remove temporary files from the SD card