For the most part, kettlebells take care of themselves if you store them in a dry spot — especially if they’ve got rubber coating. You might opt to check your bell over every few months to lightly sand down places where it might chip if you’re training outside or in a garage and have been letting it hit concrete when you set it down. But, for the most part, kettlebells are pretty low maintenance.
If you opt to strip the rust-resistant coating away from your competition kettlebell to give it a more rugged grip, make sure you’re protecting your kettlebell from rust when you’re not using it (pro-tip: wipe off your lingering sweat after each session).