D.W.
Be very careful when using Acetons (nail polish remover) as Jeanette recommends - it can melt synthetic fabrics.
Our daughter took a red pen to the new light gray leather interior of our car. The recommendation I found most prevalent for ink was to use rubbing alcohol (that's why hairspray can be effective - it has a high alcohol content).
I'd also recommend Oxyclean. We had an issue with an orange crayon, and the oxyclean spray was the only thing that took it out of all the fabrics.
Peroxide will bleach some fabrics and is usually most effective on protein-based stains such as blood.
Good luck! Some of my best stain fighting tricks have come from the Queen of Clean's website.