I would wear disposable clothing and use a Roller or better still "Paint Runner Pro" available from Teleshopping (always advertising on TV here in UK. They sound American.............
use epoxy paint and a foam roller
I Used epoxy to resurface out kitchen countertops. You can check out my link on resurfacing countertops with epoxy here. :) My favorite epoxy is stonecoat countertops. They have TONS of youtube videos on resurfacing countertops with epoxy. :)
I've done this twice already, you can see the painted granite how to here: https://thehoneycombhome.com/diy-granite-countertops-yes-really/ and the painted marble look here: https://thehoneycombhome.com/how-to-paint-kitchen-countertops/