I know this is shitty admin but I'm a sysadmin whose only qualification was a BSc in Ecology.
You're never gonna be a specialist for anything cause you're simply missing the basic principles, which are harder to learn on the job than in a classroom.
So your focus should be to become the generalist, the person with the broad overview, the one in charge of maintaining documentation, and keeping an eye open for what your colleagues have issues with, or what eats their time, then bringing that to the attention of the team.
(With good communication skills, you'll end up in a managerial position. Without, you'll stay stuck in a tech support role or become a redundancy.)
The most important skill you have to learn is: Whenever you are missing information, deal with that immediately. Look it up. If you can't find a place to look it up, ask. Then document. Even if you feel like that missing info is something "everyone" should already know. When I started out, I didn't know what an IP address is.