Ross Jeffries is one of the first, and certainly among the most advanced PUA instructors.
I am not saying that you can't learn something from David (DeAngelo) or other programs.
However, Ross Jeffries teaches lots of techniques that involve the use of language,
based on NLP or hypnosis techniques, that can be much more effective
(for your confidence and for the effect on women) than merely trying to be funny
or pump yourself up to having confidence using positive thinking techniques.
Remember, Ross Jeffries was the one who introduced us to Mark Cunningham
and the "Build a Better Girlfriend" program.
You would be surprised how much other material actually originated with Ross Jeffries.