I think it also helps if you do stuff on your own. Ie: run your own Unix server, build kernels, implement various services, and experiment with all aspects of administration. There are plenty of books out there to. An admin role is not a good starter role with no admin background. A first level help desk/support might be a good start.

take on any opportunity you can to do something with UNIX, even if it means working for free. This will pay off in the end.

Become self sufficient and learn shell scripting. Having the capability to write a script for anything proves very helpful as an admin.

here is another tip that will save you and your fellow co-workers much pain. Do it because you enjoy to do it; learn it, live it, breath it and you will be fine.

here are several commands I would become very familiar with. there are many more but this is a good start.

man
sed
awk
find
xargs
more
grep
less
tail
head
cat
cut
tar
sort
uniq
diff
cpio
crontab format
ssh/scp