Follow these window cleaning steps for professional results:
Outdoors, sweep the windows, tracks, and sills with a broom. Indoors, vacuum sills and frames. Dip a cloth into the cleanser. Squeeze it out gently. Wash the windows, using circular strokes, working from the outside in.
Wipe the glass with a squeegee, paper towels, newspaper, or lint free cloth. Use vertical strokes on the outside of the window and horizontal strokes inside. This makes it easier to see if any streaks are on the inside or the outside.
Wipe away drips around the edges with a chamois dampened cloth or let them air dry. Dry the windowsill with a rag.
Cleaning Tips from www.maidsway.com