1.) Get a machine.
2.) Install CentOS on it.
3.) Dogfood (use) that machine full-time.
You'll be up to speed in no time.
The main issue is that this is a server which many people will use and there are some business-important services that will run on it.
I'm definitely planning on installing and using CentOS as a personal machine to help learn.
I was thinking more along the lines of security and monitoring.
1.) Get a machine.
2.) Install CentOS on it.
3.) Dogfood (use) that machine full-time.
You'll be up to speed in no time.