No wrong way, there’s a better way though. I think the air compressor lays it on way thicker and into more nooks and crannies than the aerosol method. Also, it’s cheaper in bulk vs the aerosol cans. I have some extended tips and a 360* wand tip for going over the front fenders and a couple other spots. I buy it by the 5 gallon pail and I am thinking of stepping up to the 55 gal drum for next season. I spray quite a few Toyota 4X4’s yearly as Fluid Film is my side hustle.
Again, any fluid Film is better than none at all but shooting it with an air compressor is really effective.
Regardless, Fluid Film saves vehicles, I’ll never not spray a vehicle I own for the rest of my life.