theres basically two programs that can brick you wii easily, most others you would have to try to brick it with some knowhow, and Im not even sure how
the two programs to be careful with are:
-AnyRegion Changer (only use version 1.1, and obey the warnings in the readme, etc.) just dont even use cIOS downgrader, its not as good
-Wad Manager/Installer (don't install wads that aren't verified as good dumps and you won't have problems)
thats really it, everything else is very safe, assuming your power doesnt often cut out randomly, and even then, pretty safe.
AnyRegion Changer can create opera bricks, read up on that.
Wad Manager/Installer bricks, banner bricks, come from bad banners in homebrew/injected wads. read up.
things that supposedly could brick your wii, except no, they dont, not even a little:
-Starfall
-cIOS
-DVDx
-Title uninstallers (there are a few, but all have built in brick-protections, the only way to make them dangerous would be to take the available sources, remove the protections, and recompile them)
Gamecube Homebrew Launcher has its own possible issues, but not brick-worthy ones.