make sure it is dried and stuck onto your helmet. I have seen Rustoleum peel off like skin if not completely dried and stuck to its target
Lightly sand with 400 grit. Gently wipe with mineral spirits on a sturdy paper towel.
After it dries, I wipe my cleaned, dry hand over it as a final once over, then spray
Spray past the target then slowly sweep it over your target, past the other side of your target.
I like putting helmets on a post, that way I can orbit around it with spraying sweeps.
Spray a light coat. Top down, try to avoid dripping down sides or pooling at the bottom