This isn’t really that big of a tip, but we just replaced a fixture in our kitchen and this required we repainted the ceiling due to the new fixture having a different footprint. I just grab a bunch of the main off-white paint sample cards at the store and then I find one that matches. It would be good to reprint the entire floor’s ceiling, sure, but maybe at another time.
This could be done for other areas when you need a touch up.
Don’t worry about the extra paint swatches you may end up with, you can put them to use with crafts for the kids! (See Pinterest for Paint Swatch Crafts.. hopefully people don’t take them to specifically do this but its a good use if you end up with them for real needs!)