whats your hidden secrets to cleaning hard to deal with stains?

I am always looking for ways to get rid of stains.. As a parent there is always a new stain to deal with. Whats some of your fixes on stains? I will start with one I know
I worked as a housekeeper/laundry person at a local motel. I learned that the easiest way to get rid of blood is to use peroxide. I had never thought of it .. but when i did think about it sure made sense... ( you will not believe the nasty things people leave in motel rooms... EWWWWW)