1 Assemble model
2 fill ALL GAPS
3 sand EVERYTHING down with fnier and finer grades of sandpaper (any single spec or imperfection will be visible).
4 Airbrush black over everything to be metalized (yes, black, it brings the shinyness out in the metalizer)
5 Airbrush the metalizer (be sure to thin it according to what it says, I guess) onto the parts you painted black. Go for an even coat.
6 I'm not sure, but I THINK you have to buff the metal. Not sure if you use a buffing compound or not
I've never used metalizer, but that's what I've picked up from ARC forums.