After install a fresh arch with lighDM and Xfce on my ssd drive, I was looking for fastest way to boot my system in to working mode.. So i have decided to enable autologin for my lightdm and not waste time on entering password. SO here are the steps from Arch Wiki that worked for me..
Edit file /etc/lightdm/lightdm.conf and set this..
LightDM goes through PAM even when autologin is enabled. You must be part of the autologin group to be able to login automatically without entering your password:
# groupadd -r autologin
# gpasswd -a username autologin
And that worked in my case.
Note: GNOME users, and by extension any gnome-keyring user may have to follow the instructions at the end of the previous section on enabling autologin.
To create a new user account that logs in automatically and additionally able to login again without a password the user can be created with supplementary membership of both groups, e.g.:
# useradd -mG autologin,nopasswdlogin -s /bin/bash username