I have a dry scalp that gets itchy - because my hair is colored, I try not to wash my hair too often to avoid stripping out color. That means that when I do wash my hair, I need to make sure it 1) gets clean and 2) isn't too harsh.
While I recommend going to a professional to lighten your hair, there's great options for maintaining color between washes. Right now, I've got bright pink/fuschia colors. Red family pigment particles are larger and tend to wash out more quickly, so ...