Use this checklist when you go to the store and purchase your items.
Fill the bucket with water, and add a squirt of liquid dishwashing soap. A good grease-cutting dish soap also cuts through grime and bugs on windows. Don't use commercially prepared sprays and wadded paper towels on exterior windows because they'll just smear dirt around.
Soak your natural bristle brush, sponge or T-bar window washer completely with the soapy water, and start washing the glass, loosening the dirt. Wash from top to bottom. Work on one windowpane at a time, and finish each pane before moving on to the next.
Sometimes rainwater will leave marks on windows that basic washing won't remove. Use super-fine steel wool (000- or 0000-grade) to remove these stains. Don't use any cleansing powders because they're abrasive and scratch glass.
After washing the glass, wipe the windows with a squeegee. If you're right-handed, place the squeegee into the top left corner. Pull it from left to right. Wipe the squeegee clean after each pass with a lint-free cloth to keep the blade clean and your window streak-free. If the squeegee squeaks with each pull, there's not enough soap in the water. Add more dish soap to the bucket of water and begin again.
After you use the squeegee, the glass may be wet and soapy around the edges. Wipe the edges with a dry chamois cloth.
After all panes of glass in the window are clean and dry, take a wet, old towel and wipe the windowsill clean. Don't touch the glass while wiping the sills.