Should you want to get rid of minor dirt stains without using harsh chemicals, consider using a mild detergent containing white vinegar. In order to make the washing formula, mix two parts white vinegar with one part washing liquid in a bottle.
After cleaning off any remaining scum, it's time to give the door a good polish. Spray your door down with a bottle of commercial glass cleaning solution and focus on any remaining streaks. Wipe it clean with a microfiber cloth.