It's really simple if you have time and all.
You can use two types of paint.
Caliper Paint - which usually comes in Red, Orange, Blue and Silver, all flat base colors
or
Engine Paint - which comes in a few more colors including metallic etc etc.
Whatever paint you choose make sure it's designed to withstand high temperatures. Normal paint will flake/peel off.
Prep the calipers
Depending on the condition of your calipers (brake dust, age, etc etc) don't rush and clean them thoroughly. Things like metal brush or even a bbq brush, to get stubborn dirt off, brake cleaner, steam cleaner, and if you want to smooth it out, sand paper. Always wash it thoroughly when done cleaning and allow to dry out completely.
You can remove the calipers off the car, makes it easier, You can partially remove the calipers and mask the main caliper and everything around it to avoid overspraying or you can cover up the areas you want to spray. Make sure you don't spray on everything, like brake pads, clips, hoses, rotors. Make it look good
Apply a few very thin layers of paint and let it cure, follow the instructions on the can. When done painting it is a good idea to allow the paint to cure overnight.
That's about it.
