The inside of my car windshield gets filthy (and I don't smoke!), so I tried making my own windshield cleaner from equal parts of rubbing alcohol, ammonia, and water. It worked, I suppose, although there were some streaks.
So I decided to work on the streaking angle. This time, I used an old sock with a hole and water. After I rubbed the windshield, I went over it with a squeegee to remove all traces of water. Guess what? That worked really well!
So pick the window cleaner recipe you like best or use water; my best advice is to use a squeegee immediately afterwards!