Our best luck at NVCL has been with folks who find their way to our flying circles. Previously, the club did demos at aviation events, scouting events, so we have the trainer technology and instruction methods. In our case, we keep the ready to go trainers in the mower shed. We get both brand new people and people coming back to C/L. Most have some interest in aviation or history and enjoy the outdoors.
As far as IC vs electric, we use IC for that, as the power plants are more durable. An ESC may not survive a crash, and the gear (motor, ESC, timer, batteries, charger) is heavy and expensive. At the height of our annual Stuntfest contest, a dad with four kids in tow walked up, ages 6-9, roughly. After a brief tour, I asked the kids which they liked better, and they went for IC.
Somewhat related is getting folks back into flying. At least half our new members come from the ranks of "flew yesterday's planes." This presents a challenge, as the some electric flyers would rather you didn't fly pulse jet, D speed, carrier, combat or even a Fox 35 on a Ringmaster in the next circle.
Peter