Use car specific window wash and newspaper or a microfiber cloth to clean the inside of a car windshield. Wash windows out of the sun when it is cool.
Car specific window cleaner does not contain ammonia like household window cleaner. Ammonia is harmful to the materials in a car and dangerous to a person's health. Guide to Detailing recommends not spraying the window cleaner directly to the window as you can overspray causing residue on the dash and upholstery. Instead spray the cleaner directly to newspaper or a microfiber cloth.
Choose newspaper or microfiber cloth instead of paper towels or regular towels. Paper towels and towels leave lint reducing clarity through the window. Newspaper is beneficial as it's mildly abrasive aiding in clearly cloudy residue. The ink acts as a window polisher. Clean the inside of the windshield out of the sun when it is cool as windshields that are too hot cause cleaner to dry too quickly leaving streaks and residue.