DIY mirror cleaning is easy and effective. Your mirrors will show nary a streak if you wash them with equal parts water and white vinegar. But it's your technique that matters: Spray-cleaning a mirror can end with moisture seeping behind the glass and turning the silvering black. Instead, dip a clean sponge or wadded-up newspaper (sans colored ink) into the solution and clean the mirror. Wipe dry with a soft cloth, a paper towel, or more newspaper.