Before you start trying to remove a stain, read the care label on the stained clothing. Some labels forbid washing in warm water, or washing in water at all. If the label says "dry clean only," it is best to allow a professional dry cleaner to try to remove the stain. You can use a product made for home dry cleaning, such as Dryel, though the heat of the dryer may set the stain further.
Stain Removing Detergent
Some detergents, such as Tide or Cheer, are designed to remove stains when pour directly on the stain. You can then run the fabric against itself to work the detergent into the stain, which may start to break up the stain. If the fabric is sturdy, you can place a towel under the stained garment, pour the detergent on top of the stain, and then use a toothbrush to work the detergent into the fabric. Small, circular motions tend to work better than a side-to-side motion.
After treating the stain with a stain-removing detergent, soaking the garment in very hot water will help to reawaken and remove the stain. Make sure the care label of the garment does not forbid washing in hot water. After soaking for several hours, wash as usual.
Consumer Stain Removers
Portable stain removers, such as the Tide-to-go pen, or portable spray bottles of Shout, are popular for stain removal. These are more effective for pre-treating a fresh stain than removing a set-in stain.
Companies such as Resolve also make stain removers that spray directly on a stained garment. These can be used on set in stains as well, to varying degrees of success. Rubbing the stain remover into the stain helps with these in the same way as it does with stain-removing detergents.
Stain boosting laundry add-ins have gained popularity lately. Tide Stain Remover is designed to simply add to an entire load of laundry to remove stains, as is Spray 'n' Wash Bright and White. These stain removers work best when used with warm or hot water. Allowing clothing to soak in the mixture of stain remover and detergent before completing the wash style can also help remove set-in stains.
Household Items for Stain Removal
Many household cleaners can be used for stain removal if detergents and consumer stain removers do not work. One of the most popular household items for stain removal is bleach. Bleach should only be used on white garments, and is better to use diluted with water than poured directly on the stain. Many care labels forbid bleach, so make sure you check the label before bleaching. Bleaching works best when mixed with hot water (one cup per wash load, according to Clorox), and the garment should soak in this mixture for an hour or more.
Borax is another household cleaner that is often used for stain removal. Like bleach, it can be added to hot water (1/2 cup per wash load, see reference 1) and allowed to soak.
Vinegar can be used to remove crayon stains. Adding 1/2 cup to a wash load and soaking in hot water can remove waxy stains.
Spraying rubbing alcohol directly on an ink pen stain can remove the stain, most of time.