General

Upgrade and update

sudo apt-get update && sudo apt-get upgrade

Allow PPA's (Personal Packages Archives)

sudo apt-get install software-properties-common

Prevent overheat and save battery time

sudo apt install tlp tlp-rdw 

Adding Elementary Tweaks (Extended system settings)

sudo add-apt-repository ppa:philip.scott/elementary-tweaks
sudo apt-get update
sudo apt-get install elementary-tweaks

Preloading often used applications

sudo apt-get install preload

Applications

sudo apt install vlc // Video Player
sudo apt install libreoffice // Office Package
sudo apt install transmission // Torrent client
sudo apt install steam // Game client
sudo apt-get install google-chrome-stable // Google Chrome

Tweaking

Remove the guest session

sudo sh -c "echo 'allow-guest=false' >> 
/usr/share/lightdm/lightdm.conf.d/40-pantheon-greeter.conf"

Remove round corners of the screen

gsettings set org.pantheon.desktop.gala.mask-corners enable false

Disable automatic suspend

gsettings set org.gnome.desktop.session idle-delay 0

Remove language icon in panel

sudo apt remove --purge wingpanel-indicator-keyboard 

Adding Neofetch to the terminal

sudo add-apt-repository ppa:dawidd0811/neofetch
sudo apt update
sudo apt install neofetch
sudo nano ~/.bashrc // add neofetch in there