You don't need to go spending money on expensive window cleaners. You just need a couple of common household ingredients. Be sure to wash your windows on a cloudy day so the heat of the direct sun will not cause streaks. Then you can let the sun shine through with a clear view.
Sprinkle a little bit of baking soda on a wet dish cloth or paper towel. Wash the window immediately with the baking soda on the cloth. The baking soda acts as an abrasive that will completely remove any dirt, yet it's soft enough that it will not scratch your windows.
Wet a clean dish cloth or paper towel and go over the window to remove any baking soda. It helps to have a bucket of hot water near you for this rinsing process.
Mix equal parts of water and vinegar in a spray bottle. Spray your window with the water and vinegar mixture and wipe dry with any dry cloth or paper towels.
Buff the window after it dries with a soft chamois cloth or a clean chalk board eraser. Buffing will give your window a fantastic shine and you will be left with clear, streak-free windows.