The Linux Documentation Project Guides
tldp.org
tldp.org
It's fine for learning, but a hassle otherwise. Their wiki is becoming less useful too with their idea of providing less step by step and they want you to read everything and figure it out. Again fine for learning but sometimes you don't want to spend the time.
But I'm a user, not a sysadmin so maybe it's not aimed at me.
I use Fedora with XFCE.
I highly suggest Antergos [0]. It's a pre-configured, easy to install Arch Linux. I switched to Antergos from Ubuntu mainly for the 'rolling releases', the good Arch documentation and the package registry (AUR, etc.). It's the best Linux experience that I ever had. I love the rolling releases.
There's no shortage of more recent material that is less useful than combining TLDP with manpages of new commands..