[lmickh]

I would suggest looking into the Redhat certifications. Even if you don't want to take the test, they cover a wide range of topics that will give you a good base. The list of exam objectives alone will point you in the right direction to get started. You aren't likely to brush into things like autofs just playing around at home. But something like that is much more common in larger environments.

Learn to do things that you read about in system admin blogs. Spinning up VMs, clearing log files, and setting up monitoring systems. Learn to roll your own package. Even better yet maintain one for a distro and put that on your resume.

Make a effort to become familiar with several scripting tools. You don't have to master them all, but make sure to pick up enough to be able to read code in bash, perl, python, and maybe even ruby.

The final step to being a Linux admin is learn Windows. Most real world jobs require that you have to deal with both. Even if it is not your primary responsibility, you will need to know how to inter-operate with Active Directory and the services that hang off of it.