if you don't happen to have anything you can stick over your hair, that's still kinda ok, but you basically want to like... make sure you don't touch things and have an old towel you can use as a cape
Smear Vaseline or thick conditioner into the part took don't want dyed before you apply due and be super careful. Also gonna need some wrap of some sort on top of that probably.
I want to try to dye just the top. Like, leave out the short bits on the side, even if I haven't done the undercut in a few months.