I put a small amount of shaving cream on a clean surface.
I take the paper/card stock and place it face down on the shaving cream mixture and press until the card stock is flat on the work surface.
I lift the paper off and scrape off the excess foam with the palette knife and let dry.
You can use the same mixture over and over until it becomes too muddy. I often like the 2nd or 3rd dipping best.