So I jumped from Windows to Linux, endeavouros btw, and would like to know:
how you keep your system clean? If you are infected how do you find out? What do you do about it then?
Install updates regularly. Don't install software from unofficial sources. If you see a recommendation like run curl something | sudo bash, ignore it. And, in general, don't run anything as root unless you understand what you are doing and why this cannot be done without root privileges.