These are the tools you'll need just to get started. The DA sander makes things go much quicker, 40- and 80-grit sandpaper take off the paint without damaging the metal, and a good mask is a must when working with nasty stuff like paint and primer. | 
The first thing Donnie did was take the roof down to bare metal with the DA sander, ensuring perfect adhesion and avoiding a possible chemical reaction with the old paint. | 
Mask off the entire car, starting with the trim around the roof. Keep in mind that clearcoat can get into the strangest of places, and it can be a major pain buffing overspray off already finished panels. |
Next Donnie sprayed the roof with gray epoxy sealer primer. Try to use matching colors from the primer all the way to the 'flake. When using gray sealer, the silver basecoat will have less to cover, and the silver 'flake will look great on top of it all. | 
The roof was rust and filler free, so this step was necessary to seal the metal. | 
Once the sealer was dry, the roof was sprayed with polyester high-fill primer, which provides lots of material for sanding and blocking straight. Guidecoat everything with a black spray can, and block-sand the roof as straight as possible--waves will show up in the finished product. |