Make sure the windows are out of direct sun and cool to the touch. Take a clean, folded microfiber cloth and use 1 spray per 2-foot-by-2-foot square. Wipe with fast overlapping passes in a ‘Z’ pattern. Flip the towel to the dry side and make the same ‘Z’ passes again. If there is streaking, 1) your towel is dirty, 2) using too much product, 3) trying to clean in direct sun/heat.