I am not on my computer but a couple of ideas I had:
1. Match people with similar personalities (measured by the big 5). This idea hypothesizes that similar personalities can help each other.
2. Match people per topic. This idea hypothesizes that experts can help non-experts.
Matching older people with younger people and allowing them to chat regarding their lives can give a time traveller type of effect. Here is someone who's done what you want to do and walked a similar path beforehand already.