Truth be known I use Milk Bag Ties. Not because I can't afford the 5 cent pick but....they have a hole in the middle so you never drop them on stage, You can cut them to any shape you like, and after they are cut you can execute pinch harmonics much easier due to their shortness.
Get the edge of your thumb down near the end of your pick. (that closest to the string) Pick your note....
1. Your Pick Hits The String
2. Your Thumb Skin Hits The String
Sounds easy, requires practice.
Billy Gibbons of ZZ Top plays with a metal Mexican Peso Coin to give him sharper pinch harmonics.
All the best!!!!!!! :cool: