Remove any excess paint with a damp cloth or rag that you do not mind throwing away. Flush out the stain with warm running water, starting from the back of the clothing item. Create a solution of equal parts dish-washing liquid soap and warm water. Rub the solution into the stain with either your fingers or a different, clean rag to attempt to remove any remaining paint on the garment. Rinse the item, and repeat the process if necessary, to remove any remaining paint.
Wash the item as directed on the tag. Pour any detergent used in the wash directly on the stain prior to placing it in the wash for extra stain removing power. Inspect after the cycle ends. If the stain is not completely removed, repeat this step until the stain is removed. Do not dry the garment until the stain has been removed.
Bicarbonate of Soda can also be mixed with water into a paste and rubbed into the stain. Soak for a few days and hand wash regularly.