The best way is to wash it off with running water as soon as you see it, the sooner the better. The longer you leave it the greater the chance of damaging the paint. Regular washing and polishing is a way of protecting the paint and making it easier to clean when something is deposited on it. But speed is the essence, when something does happen; don’t leave it too long before doing something about it. If the paint has been damaged try cutting and polishing it.