What causes hard brick in LG G2? topic

Since there are numerous threads how to fix hard brick on LG G2, I found no threads regarding how to avoid these particular bricks, and what are the mistakes that cause them on LG G2.

Any experience or concrete example would be greatly appreciated.

Please avoid using general useless statements like the one below:
"If you want to be sure never to brick your device then just use it as it is."