Freshman
change boot timeout
sudo gedit /boot/grub/grub.cfg
then change timeout to 1 as below

timeout.png
remove unnecessary package and orphan package
sudo pacman -Rns libreoffice-fresh
remove some shortcuts
#to below directory and delete some shortcuts(*.desktop)
cd /usr/share/applications/
modify mirrorlist (no need)
gedit /etc/pacman.d/mirrorlist

mirrorlist.png
Best method is
sudo pacman-mirrors -i -c China -m rank
modiry hosts file
wget https://raw.githubusercontent.com/lennylxx/ipv6-hosts/master/hosts https://raw.githubusercontent.com/googlehosts/hosts/master/hosts-files/hosts
#then
sudo gedit /etc/hosts
Synchronising and updating
sudo pacman -Syyu
install yaourt
about yaourt
sudo pacman -S base-devel yaourt
install software
yaourt software-name
##examples
yaourt visual-studio-code
yaourt typora
yaourt firefox-dev
yaourt gromacs