The most effective solution for cleaning glass shower doors consists of a mixture of white vinegar and baking soda.
Firstly, you should spray the shower glass with water from the shower handset, before saturating the glass with white vinegar. Filling a spray bottle with white vinegar is the easiest means to do so.
Then, apply baking soda to a scrub sponge and get scrubbing! The vinegar will dissolve soap scum and debris, with the baking soda working as an abrasive simultaneously.
Once you are happy that the glass is crystal clear again, rinse around the shower enclosure using fresh water from your shower system.