Locate the hole.

Place something behind the hole. It can be a darning egg or darning mushroom, an ironing ham, or even a piece of paper.

If the damaged area of the garment is curved, choose something with similar curvature.

In the pictured repair, an ironing ham is used.

The repair will occur entirely from the front side of the garment, so this item ensures that the garment stays in place and creates a barrier between the repair area and the rest of the garment.