Traditional polo-style placket

To construct a polo-style button placket you will need two placket pieces, each twice as wide and approx. 2" (5 cm) longer than opening. Transfer pattern markings to placket pieces and shirt front. Interface placket pieces. Stay-stitch along lines of opening on shirt front. Cut along the centre of the opening to within 1/4" (7 mm) of bottom edge. Clip into corners, making sure not to cut through stay-stitching. Fold under and press the seam allowances on one long edge of each placket piece. With right sides together, stitch the unpressed edge of one placket piece to the left front opening, matching raw edges.
Repeat for remaining placket and right edge of opening. Press seam allowance toward placket. Fold left front placket over seam allowance, aligning fold of placket with seamline of opening edge. From right side of garment, topstitch in place. Repeat for right front placket. For ladies' garments, sew buttonholes into right front placket. For men's garments, sew buttonholes into left front placket. Overlap plackets and pin to secure. With right sides together, fold top of shirt over along bottom stay-stitching line of placket opening. Align bottom edges of plackets with seam allowance of bottom opening.  Stitch along seamline through all layers. Clean-finish the seam allowance and press downward. From right side of garment, topstitch across bottom of placket. Sew buttons to shirt.