This is simple and effective. I use an ammonia and phosphate free blue window cleaner that i purchase from the local dollar store for 99 cents. I crumple up some news paper, spray it with the cleaner and scrub the window with it. The fibers in the newspaper and the crumpled surface takes care of the dirtiest windows. I picked this up when i worked at a mall. Nothin' cleans snotty sticky kid hand prints better.