What is the best way to effectively remove tough stains from fabric using a stain pre-conditioner?

To effectively remove tough stains from fabric using a stain pre-conditioner, follow these steps:

1. Apply the stain pre-conditioner directly to the stained area.
2. Gently rub the pre-conditioner into the fabric using a soft brush or cloth.
3. Let the pre-conditioner sit on the stain for a few minutes to penetrate the fabric.
4. Wash the fabric as usual, following the care instructions on the garment label.
5. Check the stain before drying the fabric. If the stain is still visible, repeat the pre-conditioning and washing process.