How do I paint a cast iron bathtub?

I've never done it, but this link has great information:

https://www.thisoldhouse.com/how-to/refinish-your-cast-iron-tub

I painted my claw foot tub with the Rustoleum epoxy kit. It looked great and I think it would have held up more than the 2 years if I had not been bathing a resistant pig in it. Those hooves, lol. I really couldn't tell you how long it would have lasted, otherwise.

Proper prep is the key. Follow any and all instructions on the kit and you should have a finish that lasts a few more years than mine did.

You want to use a kit to resurface, paint and seal it.

https://www.thisoldhouse.com/how-to/refinish-your-cast-iron-tub

Thank you everyone for answering my questions. I did end up using the Rust-Oleum epoxy paint kit. Worked great and yes, proper prep is definitely the key.