Sara--Thank you!
Leah--I asked friends from my local church to pose for me. I also recently got my mother-in-law to pose for me while she visited from Utah. Pretty much anyone who is willing to sit still for 2 hours, I coerce into posing
I've found it helps to give them a mirror to look into. That steadies their gaze, in addition to giving them a reference to make sure their expression or position doesn't change.