Summarize:

When you clean up stains on carpet, always use a white cloth to avoid transferring any color from the cloth to the carpet. A white paper towel also works well for blotting stains, but make sure the paper towel does not have any printed designs. The "clean" aspect is important, too, because a rag with old residue might transfer that to the carpet and make the stain worse. Always gently blot at a stain rather than rubbing at it, as this causes the stain to spread farther and may damage the fibers of the carpet. Start at the outside of the stain and dab toward the center of the stain, which also controls spreading. Use a portion of the cloth to blot the stain once and a second portion to blot it again. This way, you pull up as much as possible without pushing anything back into the carpet. This is the simplest method to spot clean carpet and often works without the use of stronger approaches or chemical cleaners. Use a spray bottle filled with clean, cold water, to spritz the stain. Soak the spotted area of the carpet thoroughly. Alternatively, if you don't have a spray bottle, slowly pour water on the stain. Be sure not to over-saturate it. Cold water, rather than hot, is best because hot water may cause stains to loosen and spread more. Keeping the stain centralized is important. This method is good for water-based liquids such as soda, some juices, lemonade, and tea. It may also work on food stains like chocolate, fruit juice, gravy, milk, jelly, and syrup. Water is least likely to cause damage to your carpet, so it's best to try cleaning with water before you try anything else. Set the cloth you used the first time aside and grab a new, clean cloth or paper towel. Dab at the spot until all of the water is soaked up. It may be necessary to use a third cloth if the stain is large enough. If you blot the stain, rinse it with water, and blot it some more with little or no results, move on to a method that uses a stronger cleaner than water. After you are satisfied that the stain has been removed, place something over or around the wet area to give it time to dry. Walking on damp carpet can press the moisture deeper. Damp carpet is also more likely to pick up new stains from shoes. Set up a dinner-table chair or a step stool over the stain to keep people from walking on it. Place a fan or blower on the spot to help it dry faster.
Use a clean, white cloth. Blot at the stain from the outside in. Rinse the stain with clean water. Blot the stain again with a second clean, white cloth. Block off the cleaned area to allow it time to dry.