One way of dealing with stains in carpets is to let a machine do the hard work for you! Rent a carpet cleaning machine at your local supermarket or vacuum store. Or, if you’re dealing with frequent stains, due to children or pets, then you may want to invest in the purchase of one. Simply follow the directions in cleaning the stain - you may need to clean it several times with the machine to erase it completely.
Other products you can use, is a steam cleaner. Steam cleaning is also environmentally friendly, since it uses only pure water and high heat to remove stains. As an added bonus, anything you treat with a steam cleaner is automatically sterilized due to the heat.