First, we wash the window with a 
professional detergent.  This breaks the dirt free and suspends it on the glass.

Then we scrub the glass as necessary, or 

use a razor to clean off any stubborn grime.

We then detail the edges of the glass.

Next, we squeegee off the dirty water.

This is what gives that no streak shine.

Finally, we use an absorbent towel to wipe up any extra water.