Treat a pinball deal the same as a child kidnapping. The longer it takes to work a deal the higher the chance that its a tire kicker. Anything beyond 48 hours from the initial contact "I'm interested in your game, is it still for sale?" and next response is potentially a tire kicker. Most serious buyers WANT to contact you.
Email or txt is fine at first. Once you've established some kind of connection it would be nice to speak on the phone to narrow down the deal.