Linux from scratch
At an early stage of my Linux apprenticeship I had the chance to discover their web site ( http://www.linuxfromscratch.org/ ) and I had the patience to give it a try. It takes some time to do it but at the end, besides the satisfaction of having built your own Linux distribution you will come enriched with invaluable knowledge on how an OS is working internally. This experience is distro neutral so after that you will feel at ease in front of any flavor of them. Also another important gain is that you will never feel intimidated by the sequence ./configure, make and make install, ever. Add to this reading on CentOS website about when is appropriate to compile from source and when it is not ( http://wiki.centos.org/PackageManagement/SourceInstalls ) and you've just made a long way towards safeguarding you mental sanity as a *nix sysadmin.
In the end, for those who feel ready to begin their journey in the land of Tux I will recommend as a starting point the IBM Developers website ( http://www.ibm.com/developerworks/linux/ ). They have a good collection of tutorials there.