@teenboy14:
Just turn on firewall, keep a password on, make backups to an external drive, and use a vm for anything you might think is dangerous.
I assure you that this is a rather terrible idea… A firewall alone will not protect from certain kinds of malware, especially if it supports UPnP. While it may be sufficient to prevent most internet based exploits, it does not take into account that some of them take advantages of other loopholes in the system, not necessarily limited to just exploiting things like UPnP to be able to establish a Trojan Horse style attack, but also certain other hardware exploits that do not necessarily need the internet to be able to do their harm. Such examples include ransomware, which can encrypt your sensitive information and critical system components, or even worse, in the case of one Mac virus I was hit with back in the late 1990's, it actually did physical damage to the internal hardware of the system, which effectively destroyed the entire computer beyond repair.... A simple firewall in this case would not have been sufficient to be able to save me from this attack, as the particular computer in question was only equipped with a 56k DIAL-UP connection, which was not even established at the time. Believe it or not, simply by inserting a 3.5" floppy disk into my computer that was infected with the virus was enough to take everything down.... The down side of hardware that is designed to automatically read whatever media is inserted the moment that it is inserted...