You need this:

• WD40
• Lint-free cloth

This is how you do it:

First, make sure that your shower cabin is free (as good as) of lime. Then spray WD40 on the places where you want to prevent limescale. Allow this to set in, rinse and rub dry with a lint-free cloth. By greasing your glass doors / walls with WD40, it creates a protective layer on the surface. This ensures that the lime in the tap water cannot settle on the glass. Great right?