Wipe away the paint with a damp cloth as soon as it is noticed. If the paint is still wet, it can be easily removed and leave no stain.
Soak the shoe in cold water for 10 minutes and try to wipe the paint away.
Wash the shoes in cool water with a detergent if the paint has started to dry or is too stubborn to just be wiped away.
Soak the shoes in hot water and rinse with cold if the paint has dried.