Don't. It's a bastard of a job.

Either live with the current paintjob, or pay someone to either powdercoat it or give it a proper hardcore paintjob, that's my 2c. Anything you do with a rattlecan will suck by comparison, despite putting in a ridiculous amount of effort preparing it.

Although if it's ally, you could just strip it and give it a brushed finish with some scotchbrite, like mine...