Sewing them to lapped and abutted edges. Where garment edges lap, sew the hook on the overlap, 1/8 inch from the edge. First secure the thread with a backstitch, then whipstitch around each hole in the hook. Pass the needle under the fabric to the end of the hook and whipstitch it also; secure the thread.
Close the garment. Mark the eye placement on the underlap; attach a straight eye.
On a garment where edges meet, sew the hook 1/16 inch from one of the edges. Position a round eye on the other edge opposite the hook, extending it 1/8 inch beyond the edge. Whipstitch around both holes in the eye and on each side of the hook.