Get an old spray bottle and fill it with very dilute washing up liquid , like 1/2 a teaspoon in a gallon of water. Spray windows and polish off with old crumpled up newspaper . Never fails, very cheap, perfect windows, no smears.
As soon as the newspaper gets wet just use another lot so the windows are never allowed to dry on their own but polished dry. I clean windows in a large community centre and this is how I do, it tried everything but this is simply unbeatable. You just need to be generous with the old newspaper , it just goes in the recycle bin afterwards so very 'green' and also virtually free .