Answer: Have a face-to-face meeting when you start the relationship
Distance relationships can be very productive. Breaking the ice and establishing rapport is so much easier, face-to-face.
Begin with a function that brings participants together. The investment outweighs the cost of a failed relationship.
If you cannot get together use videocalls (such as Skype), which is better than email or an ordinary phonecall.
Extra work is necessary to ensure the viability of the long-distance relationship. Extra contact and newsletters help. You may wish to provide participants with regular mentoring articles? You will find a lot of them here at this blog.