Non-greasy marks: Warm water spot clean with half a spoonful of any standard washing powder in a cup of hot water. Blot the stain with a cloth or a sponge dampened with this solution, working inwards from the outside of the stain. Do not rub it. Once the spot is removed, sprinkle the area with clean water to remove possible traces of powder. Do not use stain removers. If using a chlorine-rich cleaner, do not leave it to dry in direct sunlight. 

Oil or grease spots: Butter, oil, lipstick and the like must be removed with acetone. Once the mark has been removed, apply a solution of washing powder to the fabric and rinse it off with clean water exactly as for stains that are soluble in water (see above).