feel free to joke around, talk about things they like, or simply compliment them. This can make them feel more comfortable and bring about natural smiling and laughing, as well as fill in the silence

Oh, I agree with this completely! People are often too conscious about they way they look and things like wrinkles or skin that isn't perfect enough and it makes the overall look tensed. You can get rid of eye circles or double chin in a few clicks in Photodiva ( here is a good article on that btw), but you can't achieve this relaxed look in post, so it's important to help your clients feel comfortable around you, and the best way to do so is talking!