Heres a few tips to keeping those windows clean:
1) Clean one side of the window with horizontal strokes and the other with vertical strokes, exposing which side is streaking
2) Using an old newspaper offers a greater shine than cleaning with a towel or sponge, plus, newspaper leaves a transparent film behind that is resistant to dirt
3) Using wax, lemon juice, lemon oil or even tooth paste to polish the windows on a regular basis will prevent chemicals from etching water spots onto the glass surfaces
4) If windows are in need of heavy cleaning try some CLR. Mix in a bucket and brush onto windows, let dwell, then use a hose or prep gun to remove.
Hope some of these will prove to be helpful!
