here is myquik rundown of howi have done it on previuos cars, last one being a silvia s13.
step 1- remove wheel and make sure car is in solid position
step 2- remove caliper off the disc and clean the hub with degreaser and a steel brush, the same but gentley with the caliper.then clean off with warm water and let dry
step 3- sand the hub lightley, try and do the biger areas on the caliper as the detailed bits are tricky, try usind steel wool, u just needto give it a light sand to prep the surface, then clean with water again and let dry.
step 4- cover up areas that may attract overspray, i cut out a ring that finishedflush with the hub, which covered the disc. then paint firstly with a metal primer.
step 5- once this is dried properly,paint with your colour, after letting this dry u might want to apply clear aswell.
step 6- once all is dry, take off covered stuff and put ya wheel back on.
its a very simple process that takes a good day to do, and is cheap and will last forever if done properly, like i said this is how i did it and it worked great.
also, with the nissan sign on the caliper, i actually dipped a cotton bud in turps and wipped off the paint on the nissan when it was still wet, i then sanded it with fine grade wet and dry paperonce dry, whick brought it back up to the shinny finnish, alsoused some metal polish for a finishing touch.
have fun!