Whenever I buy a new spool of thread, I mark the notch on the spool with a black marker. Then I know which direction to load the spool on the spool holder on my sewing machine. The marked/notch side should alway point down or to the right. I started doing this after my thread got caught in the notch when I was sewing.

To remove pencil marks from your quilt, try this recipe: 1/4 cup water, 3/4 cup rubbing alcohol, 7-8 drops of Palmolive detergent. Mix together. Apply with toothbrush, rub gently.

The easiest way to wash a quilt is in the washing machine:
Use your machine as a giant washtub. Fill it with water, hand agitate the quilt, let it sit for a while, and let the machine spin out the excess water. What soap should you use? Any kind of mild soaps such Ivory Soap Flakes, Fells Naptha, or Orvus. Equal parts of Dove Liquid dish soap and Clorox II Powder in hot/warm water also works well.

For a natural solution try this buttermilk mixture:
For every gallon of water, add 1 Quart of Buttermilk (butterfat content 1% or less) and 1 Tablespoon Lemon Juice. Make sure you rinse it out well! If your quilt is really dirty, you may wish to use a detergent or enzyme cleaner like Axion or Biz.  No need to soak for more than 20 minutes.