The basic premise is this:
1 part dawn dish soap
2 parts hydrogen peroxide
mix, pour on stain, scrub it in, and then allow to sit for an hour or so.
I decided to try it on two of my worst stained items of clothing: my cream camisole, and my 'little miss bossy' tee shirt, both of which I've had a long time and have worn frequently, often in the summer months. I failed to take a picture of them before putting the solution on so here you see them with the solution on them: