Depends on the condition of the paint. Does it have scratches? Swirls? What polish are you going to use? A polish is going to actually "cut" the paint. The wax is just going to add shine and protection. If you have scratches/swirls you're only going to cover....temporarily. Do it once....do it right. If you have tools and time.

I would probably start with a light rubbing compound then up to a polish. Then maybe a glaze. Then your was/sealant.