I don't think unix admin courses are much good - you have to learn and experience unix on your own and no training course can replicate that. Training is good for learning specific skills quickly once you're more established.
The best way to learn Unix is to get your hands dirty.
Get yourself a Linux distro, and play around with it. Use it on your home computer. Do things on the command line that you would have previously done by pointing and clicking.
Learn to program. Perl is useful. Bash ( or ksh ) scripting ( for a unix admin ) is vital.
Look through log files, find problems find out what they mean. Fix them. ( hint: google is your friend )
Google for "esr smart questions" without quotes, and read it.