How to Make Debian/Kali Linux Safer ?

Hi, I want to use kali linux as my main os, and to make it safer, I gathered these ways: using non root account, using vpn (such as airvpn), using noscript add on, blocking ads, being intellegent about what I click on and who I trust,

But should I use iptables (or another firewall) ? And should I encrypt the drive/data ?

Also, can you give me another ways please ?

Thanks in advance.