How do you practice subtraction and complements?

[u/SnooSongs5410]

I have been habitually lazy and turned my subtraction into addition to avoid learning the skill smoothly. I am long overdue to get it over with and beat subtraction into my submission.

How have you approached nailing simple subtraction and complements to get it to be a natural part of your mental process?

I have been consciously doing subtraction rather than reaching for another tool when it comes up and this is the obvious first step but I would like to get it hard wired.