Ask them for their social media pages (Facebook, Twitter, Tumblr, Instagram.) Ask them to Skype with you beforehand. Ask them to snap a pic of themselves with your name handwritten on an index card. Ask them for a bit of background on themselves without being too specific (what kind of job they have, what their geek loves are, how they found out about the club, if they go to school, etc.) If they are a true friend, they will understand your safety concerns!