Ok it is not a secreat but many of you will not want to hear it. It is quite simple. Good instruction followed by a high volume of purposeful practice. That is it. After years of chasing secrets my swing has changed from sever over the top to a nice inside out.
The secreat two lessons a week from an instructor who can explain what I need to do in many different ways and give be a practice plan to get there. Then 20 plus hours a week of quality practice. Changes are incremental and build on each other.
It has taken me 3 months to get to this point still many months to go.