That's fine tradegirl, I just read it both ways and wasn't really sure. I think the few techniques I use are pretty basic, don't pounce on them the minute they arrive, but don't ignore them either. I just nod my head, say hello and leave them for a couple of minutes. If they are still there then is the time to approach. Control the conversation, but don't be too pushy, and get them sat down and away from their part ex as that reduces their emotional attachment to it. They think more clearly when they aren't looking at their dearly beloved (knackered) old car!
I often reward the nice customers who don't ask for a discount or quibble about the price, by throwing in an extended warranty or chipping £100 off the price. I already had them on the hook, the deal was done, but that gesture will stick in their mind for next time.