Default [Q] Rules of Flashing

Can someone make a list that shows how to flash and not flash?

Locked Bootloader with Root:Custom Kernels, Mods, Custom Roms, Custom Kernels, Stock Kernel?

Unlocked Bootloader with Root: .................

This way we have an easy way to know what to do and what not to do.

If you feels this is an unnecessary thread, just ignore it and let it die.