The Art of Social Engineering
About 90% of the attacks today have some sort of social engineering, master the art with this 3 days course, Master OTW will walk you through the tools you need to be a good social engineer.
Art of Social Engineering Day 1
Art of Social Engineering Day 2
Art of Social Engineering Day 3 Part I
Art of Social Engineering Day 3 Part II
The skill you need to have if you are about to get into the most sophisticated systems.