I use Rain X windows cleaner. Make's the windows/windshields clean and clear and at the same time applies a coat of Rain X which causes more beading to rain as it hits the windshield while I'm driving.
<<<< another stoner's invisable glass user and I'll swear by it day in and day out especially sence I smoke in my truck. Spray it down wait a few seconds wipe it down with a clean rag then repeat with anther rag to remove any possible left over area's, repeat twice for extremly dirty windows and that's it. Also it works good on the "Frosting" of headlights if you let it soak in for a bit it makes quite a difference.