Question: first things to do after installing debian 9?
Answer: Update. sudo apt-get update && sudo apt-get dist-upgrade -y.
Install SSH. sudo apt-get install ssh.
Install VIM. sudo apt-get install vim -y.
Set VIM to be the default editor (crontab) echo 'export EDITOR=vim' >> $HOME/.bashrc sudo update-alternatives --config editor.
Install ifconfig. ... 
Install byobu.