Next to all above good advise:
1. Learn to *listen* to your users
2. Learn to *read* error messages (and where to find them)
3. Learn to *write* logs of what you do, so you can tell your boss what right and wrong on your systems
4. Learn to read *scripts* (ah, awk, sed, perl). Lots of SA tasks are done through scripting (cron, at, ...) and you /need/ to be able to read them. If you can read, the next step is to understand, and after that being able to actually create your own scripts will make your life a whole lot easier.
5. Learn to be patient. Being an SA will prove to be completely different than being an (end) user.
HAVE FUN!
Enjoy, Have FUN! H.Merijn