I usually convert PDF to raster and draw over. White or light gray box overlay will save ink/toner for everyone and is just as opaque as a black box.

I still do pixelize with huge pixel size when information is not that important. I think it better conveys that there was something there, and redacted areas look more organic.

Pixelation, just use less squares, I pixelate to one line of huge squares.

I would not be so sure about cutting the area, don't forget to print it (to PDF) instead saving it.