I want to put a 2 inch wide strip of 1/8 to 1/4 inch pleats on the button placket of a men's dress shirt. What are your suggestions for the easiest way to accomplish this and how do I ensure they never come out over the life of the shirt?

chalk trace your pattern. Single lay the overlap side you wish to pleat. Cut it out large enough to accomplish your pleating/tucking.Give yourself sufficient width to face the finished placket with an extra inch at center front for good measure. Maintain Grain!

Pre-pleat the front placket. Press carefully- in fact I would use a press cloth. Layout the pattern and Maintain Grain...carefully cut out the shirt overlay side. Interface the facing width behind the pleating. Construct as usual.

When you cut the underlay side make sure to remember to flip the pattern print side down and cut a single lay without the extra width you needed for pleating.

Forgot to say.1/8th inch pleat I would use a 5 tuck pin tuck foot. Do some practice on similiar weight fabric. Adjusting stitch length etc.

Kaaren