2 part hydrogen peroxide to 1 part Dawn (original blue) will take the stains out of almost ANYTHING...even if they're old stains! // Mix in a spray bottle and use as a stain remover spray- must try this!
Add orange peels (or any citrus peel) to a quart of white vinegar in a closed container and let it set for two weeks. Combine citrus/vinegar solution half/half with water and use for cleaning. Works on floors, tile, fixtures, etc. Smells good and is tough on scum! Best of all there are no chemicals.
If you need to remove collar stains from your dress shirts, you need proper tools. Organic body oil and hair oil will accumulate around the neck which then creates the ring stain around the collar on a dress shirt.