One of the things that I wish I didn’t have to do with a detail is clean the windows. I hate them! After many years of doing them however, I believe I finally have it down! I use Meguiars Glass Cleaner Concentrate, and use a two direction method. As for the glass cleaner, I mix two cups of water and the rest with water in a one gallon jug. I also use ultra microfiber towels as well. I dry the glass in two directions. Get into the habit of doing your final wipe of interior glass in a horizontal direction, and the final wipe on the exterior in a vertical direction. Then, when you find the inevitable streak, you’ll instantly know whether it’s on the inside (horizontal) or the outside (vertical) of the glass. You’ll get perfectly clear glass without jumping in and out of the vehicle chasing that streak. I always start with the inside windshield. I sit in the passenger seat, and reach across with my right hand to wipe. By sitting in the passenger seat, you avoid the steering wheel, etc to get in the way. I usually use three or four microfiber towels for the windows. Another thing I have noticed is not to use too much cleaning solution. Just a little bit will go a long way. The more you use, the more of a chance for streaks. Cleaning windows is not easy, and as I said before, if I could eliminate one thing from the car detailing service, I would eliminate the windows.