Removing Carpet Stains

The first priority is getting to the stain as soon as possible.  Remove as much of food spills as possible by scraping the carpet gently with a spoon or a dull knife.  Absorb wet spills quickly by blotting repeatedly with white paper or white cloth towels.  Always blot; never rub or scrub abrasively, as a fuzzy area may result.  When blotting, work form the outer edge in toward the center of the spot to avoid spreading the spill.  
Remove the stain using one of the cleaning items from the checklist below.  Rinse the cleaned carpet area with water to remove detergent residue that may become sticky and cause rapid re-soiling.  Absorb any remaining moisture by placing several layers of white towels over the spot and weighing them down with a heavy object.  This step is necessary even when the carpet doesn’t seem particularly damp.  A helpful tool in deciding which stain removal technique is right for your stain is the Spot and Spill removal page on the Shaw Floors website (https://www.shawfloors.com/cms/Articles).  For example:
Oil-based stains:Blot as much as possible with white paper towels.  Apply the special oil and grease spot remover (Spot remover specifically designed for grease, oil, or tar, such as Carbona or Energine) to a paper towel and repeat blotting. (Protective gloves should be worn, as the solvent will quickly remove oils from the skin and could result in irritation.)  Do not pour or spray directly on the carpet pile, as damage to the backing or adhesive underneath could result; use the towels to transport the solvent to the carpet.  Repeat as often as necessary.
Provide adequate ventilation.  Do not use flammable solvents.
If necessary, continue to: Blot the stained area with white towels dampened with cool water until there is no more transfer of stain onto the towels.
Then use the detergent solution.  Spray lightly onto the spot and blot repeatedly with white towels, working form the outer edge in toward the center of the spot to avoid spreading.
Rinse thoroughly by spraying with clean water, and then blot to extract.  Do not use too much detergent because the residue will contribute to rapid re-soiling.
Be prepared for any spill with the following checklist:White cloths or white paper towels
Detergent solution: Mix mild liquid detergent with water (no more than ¼ teaspoon of detergent to 32 ounces of water).  A clear, non-bleach liquid dish washing detergent such as Dawn, Joy, or clear Ivory is recommended.  Do not use detergents that are cloudy or creamy because they may leave a sticky residue.
Vinegar solution: Mix 1 part white vinegar to 1 part water.
Ammonia solution: Mix one tablespoon of ammonia to one cup of water.  (Do not use on wool or wool-blend carpets.)
Non-oily nail polish remover.
Chewing gum remover (freeze or solid type)
Spot remover: Use spot removers designed specifically for grease, oil, or tar.
Specialty Spot Removers: Several specialty spotting products are available from cleaning industry suppliers to remove difficult stains such as Betadine, food dyes, mustard, etc. 
Source: https://www.shawfloors.com/cms/Articles