Some basic physics applies: warm air can hold a lot of moisture. When it cools down, it releases that moisture as condensation onto cold surfaces (in this case, on the inside of your windscreen). So, if you do a reasonably long journey, expecially with a few passengers on board, or with wet coats etc. in the car, the internal air will be warm and moist at journey's end.
At the end of your journey, (especially if it is a cold dry evening) open a few doors and let the warm wet air in your car be replaced by colder, dryer air (or just open all the windows for a minute or two as you are coming in the driveway). This one step will greatly reduce the internal condensation to be found next morning.