I'd start by getting Fedora 12 installed, and then work on doing some hosted services (SAMBA, NFS, FTP/SFTP) just the sort of things your company would do. Play around with VNC, that kind of thing. Learn to start and stop services, extend file systems, tweak permissions.
Definitely play with stuff like firewalls and apache, since most companies love those.
Hard to say otherwise, depends on what they want you to do