What is your unique detailing tip?

I have read a lot of cool tips within other threads and it is gettin hard to remember all of them. In the spirit of comradierie, please share yours again, here are two of mine:

I wedge a piece of posterboard or cardboard against the windshield when I am detailing with Armour-al protectant so that I avoid the mess on the windshield. I throw the board when I am done.

I also have a small piece of claybar to polish the outside glass and remove any hard deposits that are difficult to remove otherwise. I have not seen any scratches on the glass.