I've had the idea to do black and white polka dots for a while cos its a classic style and is so easy peasy.
Start by paint the base coats on.I used alternating colours of Barry M Nail Polish. I painted on two coats for a smooth finish.
Then once the base coats are dry, start dotting on the polka dots. I actually used a dotting tool specifically for making dots in nail art. I got them on Amazon and they have no other purpose other than creating perfect dots. I used the largest ended tool for large dots but you could create a less pop art style with smaller dots.
If you don't have a dotting tool then you can just use the nail varnish brush and a steady hand.
Ta Dah!