the best way to clean the windows, and its been working for me for years, and i use this route everytime i clean a car.
1. Take about 2 teaspoons of dish soap and put it in a bucket
2. Run hot water on the soap to dissolve it
3. After the soap is dissolve, fill the bucket 1/2 way with hot water, not scalding hot, but hot enough where you can put your hand inside and not burn yourself
4. Get a microfiber cloth, dip it in the bucket, and wipe down one window at a time
5. while window is still damp, take a clean microfiber towel, and wipe window dry
6. you should have no streaks after this is done, your windows will be clean, and should not fog up as bad as if it werent clean.
your windows will fog up if there is enough condesation in the car, but taking this route will help it defog faster than other times. make sure when you are defogging windows, you dont try to wipe it off, or open them. the correct way to do it would be to put your climate control on the defogger mode, set it to bring in air from outside, and make sure your A/C is on, and depending on the weather outside, set your climate control accordingly.