[Callers] "Flash Mob" dances

Over in San Jose we've just done a second annual not-really-flash-mob dance. Symphony Silicon Valley does a free public series of Pops concerts, get permission from them, pick one, get a bunch of volunteer dancers and a pickup band, print up some flyers and put up a sign with the sponsoring organization logo and URL, We put up a sign with the name of the organization, set up in the path of foot traffic to the concert spot, and do an hour and a half (or so) of easy contra dances, encouraging passersby to join in and hooking them up with more-experienced partners. This is successful in terms of getting some exposure, and today we got somewhere between a half-dozen and a dozen new people to actually try it, and probably moved 25 flyers. Nobody got hurt, some of the dancers stayed for several dances, etc. We flushed out some old square dancers (who of course wanted to swing once around and wait for the next call) and some previous non-dancers of various ages. (I was calling. First round was missing many volunteer dancers and had multiple newbies, so I did a one-night-stand dance ("Up the Sides and Down the Middle") rather than a duple-minor contra; then Cranky Ingenuity, Inflation Reel, Kitchen Stomp, and Delphiniums and Daisies.) Posting to ask if people who've done this kind of thing have any tips or tricks to get things going. As caller I relied on my volunteer dancers to do the recruiting, and people had different comfort and skill levels doing that. Is there something I can tell them that will increase their comfort in talking to strangers? Thanks! -- Alan