This is what works for me usually. First replace those wiper blades and get some Bosch Micro Edge Excel. One of the best blades you can buy. First get some luke warm water and baking soda and mix it together. Then wash the windshield with that mixture. After rinsing and drying, take some rubbing alcohol and rub down the entire windshield, inside and out. Use as much rubbing alcohol as needed and use like a gauze pad or something like that. And then put on the new blades after you're down cleaning. Enjoy the view