On the FRONT reinforce the inner corners of 'V' neckline by stay stitching along seamlines, pivoting at small circles.
Apply interfacing to left and right plackets. Be sure to apply the interfacing to the corresponding pieces correctly. Laying it out first will help with this.
Finish the edge of the lower edge of the left placket and facing, being careful to keep the shape of the pattern piece.
Pin left placket to left placket facing.
Stitch 1/4" along placket edge.
Using a tailors point presser/clapper or tailors ham will help a lot with pressing the plackets.
Press seam open. TIP: Pressing the seam open will help create a crisp edge when the placket is turned 'right sides out'.
Bring wrong sides together and press.
Pin placket to left side of V neckline, matching circles.
Stitch 1/4" seam, ending at circle. Back-stitch. Clip 'to but not through' to the stitching of the shirt fabric ONLY diagonally. Press seam towards facing.
Turn facing to inside of shirt. Fold long raw edge of facing along seam line (1/4"). The next step requires us to stitch the facing into place by stitching 'in the ditch' created by the seam. Pin facing in place, being sure to catch the edge of the facing.
Notice that my pins are positioned along the 'ditch' in the above photo, and they 'catch' the facing on the inside, as in the below photo.
From the right side 'stitch in the ditch' to circle at bottom of the placket.
Do not backstitch. (This is personal preference, but I think it looks cleaner if you eliminate back stitches on the right side of the shirt.) Pull the thread to the back of your shirt and tie off. Leave the ends and bury them into the placket later.
It gives a very clean and professional look. (Alternatively you could edge-stitch or top-stitch on the facing if you prefer, but I prefer the 'stitch in the ditch' method.)
Pin the right placket to the right placket facing.
Stitch 1/4" along the placket edge, pivot at circle, and stitch along the bottom and up the other side to the circle. Back-stitch.
Trim the corners.
I use the tailor point presser to help me press the seams open.
Turn the placket so wrong sides are together, and press. This finished bottom edge of the right placket will create a 'tab' once applied to the shirt front.
Pin placket to the right V neckline matching circles.
Stitch to the circle. This will require you to open up the lower end of the placket as you near the circle. Back-stitch.
Clip 'to but not through' to the stitching of shirt fabric ONLY diagonally. Press the seam towards the placket. Turn facing to inside of shirt. Fold long raw edge of facing along seam line (1/4"). The next step requires us to stitch the facing into place by stitching 'in the ditch' created by the seam. Pin facing in place, being sure to catch the edge of the facing.
From the right side 'stitch in the ditch' to the circle at bottom of placket.
On the wrong side, notice how the stitches caught the edge of the facing to hold it in place.
Do not back stitch. Pull your threads to the wrong side and tie the ends. Leave the ends and bury them into the placket later.
After clipping the shirt diagonally to the circles on both the left and right corners of the placket, it leaves a little 'flap' of fabric along the bottom of the 'V' neckline. Tuck this flap along the stay-stitching to the inside of the shirt.
The left placket overlaps this flap.
The bottom edge of the left placket should also be on the inside of the shirt. Stitch through the left placket and the little flap of fabric to hold it in place, stitching close to the folded edge. This stitching will be hidden under the right placket.
With the right side up, place the right placket over the left placket, with the finished bottom edge of the right placket on the right side of the shirt front. Be sure that both sides of the neckline lines-up with each other. Pin the right placket in place, through all layers, placing your pins 'just' below the stay-stitching line, being sure to catch the small flap of fabric of the V neckline, and the left placket.
Stitch through all layers, along the stitching line marked on the pattern. This will create a 'tab' at the bottom of the placket. Do not back-stitch. Pull threads through to the wrong side and tie off. NOTE: I prefer not to stitch the tab down, however, you can do this if you want with a box stitching around the inside of the tab or in an crisscross X.
Using a sewing needle, I bury the ends into the inside layers of the placket, and then clip.
That's it! Clean. Professional. Finished.