When doing the satin stitch sections, find the center of the shape for first stitched fill in with stitches until you have covered the printed area.
Nautilus has some odd shapes to fill in. You can use one stitch for straight lines or back stitch for curved lines. You can also add more than one row of backstitch if you need it. For the triangle shapes with a line at the end, stitch the line first and then fill in the triangle shape with satin stitch. Just keep adding stitches until the printed area is filled in. Outline of the shell is backstitch.