I'm not to sure about this idea, the admins should be able to watch over the server, but some sort of system to see if a person already got a warning would be nice.

Maybe add some commands like:

/warn <Name> (Warn and show how many warns a player have)

Example: /warn Zart (1/3 warnings)

/warns <Name> (Checks how many warns a player have)

Example: /warns Ice (2/3 warnings)

After 3 warnings from an Admin the player would then get a ban of 30 minutes and the message:

Go read ZarpGaming's server rules, and come back in 30 minutes.