Painting galvanized steel carport

I'm currently building a carport (Titan kit) and I'm thinking of painting the galvanized steel frame before I put the roof and trim on. I would imagine it would need to be prepped before it is painted? What sort of primer do I use?

What's the best way to paint it? With a roller and brush? I've got a (smallish) compressor and a normal automotive spray paint gun, but am a bit worried about over spray. I thought about hiring a HVLP gun for the day, but am not sure if it is worth the money...

Etch Primer is what you need for priming Gal.

As for application, depends on the finish you want. You can get the primer in an aerosol for the fiddly bits and then brush on the rest. If you've already got the compressor and gun, then use it. Unless you're spraying directly at something, outside your "overspray" dries and turns to powder pretty quickly and will wash away with the next rain shower.