I have no secret.
I got mine from my sister about 15 years ago.
I thought it was a silly contraption but after I used it I became a fan.
I just followed the instructions.
Preheat to medium high. #8 seems to work on my cooktop. I did need to play with the heat at first. (The butterfly-mushroom thing really works)
Add the popcorn and oil. (I have used butter in place of oil) Put it on the stove and start stirring slowly and evenly.
If you add sugar be prepared for more clean up.
It starts popping in about 2 minutes and is usually finished in another 3 to 4 minutes.
Once it stops take it off the heat and dump it in a bowl. Add seasoning of choice and enjoy.
I have the bowl and seasonings ready so perhaps my luck is timing.
I try to use as little oil as I can and have found being quick with adding whatever seasoning helps it stick to the kernels.
Hey it's popcorn so experiment and enjoy.