That's a wonderful website and shows very well what to do.

In addition, if you want to, you could sew a double row of stitching across the pleated section at the waist using heavy thread. That would hold the pleats. You could sew leather ties at the outer edge of the aprons with a corresponding tie at the other side.

My teacher, Ann Stewart also attached several belt loops onto the back waist, to make it even easier to put on.