Wipe very dirty windows with a damp cloth. Don't rub dirt because it will scratch the glass. A vacuum cleaner with an attachment will work for this job, too. With a clean sponge or cloth lightly wet the window. Don't flood it! When using a squeegee, tilt at an angle to the glass, so only about one-inch of the rubber blade presses lightly against the top of the window glass. This will leave a dry area across the top of the window and stop drips from running down on your clean window. Wipe the blade of the squeegee with a damp cloth each time. A dry blade on dry glass will skip. Next place the squeegee horizontally in the dry area and pull down, lapping over the dry clean area each time. Continue until you have finished the window. Finish by wiping off the window sill. Windows can be cleaning from either side or from the top using this technique.

You may use a cloth or paper to clean also, use overlapping strokes so you cover all the window and don't miss spots.