Hi, new to Linux here and I am a bit confused as to all of these options for allowing/restricting access to a server.

Is there a best practice for restricting access to a server? Which one of the options would I use?

I inherited a couple of Linux servers and it is sometimes frustrating to adjust iptables to let traffic in on a certain IP only to find that iptables wasn't the only issue and access was also restricted in access.conf. I spent 20 minutes banging my head against the wall on my first configuration only to find out that there are TCPwrapper, SSHD, and access.conf to consider as well.

My hope is to be a half decent Linux admin sometime, so knowing what to use or when to use it in a real life scenario would be very helpful. How do you decide what option is best to use? IS there a best practice? thanks!

You just stumbled across one such best practice: layered defense/security. The real issue might be that the systems you've inherited lacks proper documentation (which could represent a security issue on its own).

When securing a resource, you first find a suitable method or mechanism with which to implement the required level of security.

Once you've verified that the mechanism does indeed do what it's supposed to to, you ask yourself this question: "What happens if this mechanism fails, or has an unknown vulnerability that gets exploited, or gets disabled or misconfigured by mistake?"

Then you implement at least one other (preferably fundamentally different) mechanism to deal with the scenario above.