The only way for someone to use an end device to infiltrate a network is if the device has a available network interface not connected to the network. For instance, if the device was connected via Wi-Fi, then the only way an attacker could get into it is by way of an ethernet port, Bluetooth, or some other network interface.
Now if you're worried about someone attacking the end device to exploit certain things, I find a way to make them physically meaningless or something. For example, I'm paranoid someone will access my TV's camera and turn it on. So I put a piece of tape over it and used a silver Sharpie to block it out.
However the best wireless network advice I can give you aside from the whole "secure your network" shpile: don't broadcast your SSID. That alone will pretty much deter everyone if they're doing anything drive-by. Unless it's from the internet. But really, if you don't want that device compromised, don't hook it up the any network.