I spray w/Zout as soon as tey come off their little bodies, again before I wash, add a bit of bleach when they are really bad (like tonight). Also I don't dry them, that sets the stain and they will never come out after that.
Here are girls only wear white until they get to Majors (12 yo). This is our 4th year with white. My son has black this year and I. Loving it!