What's the best way to pre-treat a stain on clothing with this soap?

To pre-treat a stain, first dampen the stained area of the fabric with a little cold water. Then, rub the dry soap bar directly onto the stain, applying gentle pressure to transfer a layer of soap. Focus on covering the entire stained area. For older or set-in stains, you can work the soap in with your fingers or a soft brush for a minute to help it penetrate the fibers.

Let the soap sit on the fabric for 15-30 minutes. This gives the fatty acid compounds time to bind to the stain particles. Do not let the soap dry completely. After waiting, wash the garment as you normally would, preferably in the warmest water safe for the fabric. The soap will dissolve and rinse out during the wash cycle. For delicate or colored fabrics you are unsure about, always test this method on a small, hidden area first to check for colorfastness.