Will usually get you arrested.
However, when shooting them with Cameras, about the only thing I can recommend is to get them comfortable before you even point the camera at them. Try to get them chatting about something they are passionate about (A hobby, a child, a pet, a job, whatever). Only start shooting them once they are relaxed and comfortable. the passion you got them talking about will show up in their posture, they eyes, in pretty much everything.
The big trick, as I understand it (realize I'm parroting what I've read, mixed in with some good old fashioned psychology) is to make the person *want* to be there. So give them a reason to be in the studio and happy.
Best of luck to you