Andy at the Jerx elaborates on a great way to set up a magic trick: "the peek backstage."
The core of the method here is to introduce the trick with ""Can I get your help with something I'm working on?" This sets expectations, gives the audience something to do, and tells what what you're expecting of them. As Andy points out, "Do you want to see a coin disappear?" sets up a situation in which it's impossible to know how to react, like "I'm going to sing you a song! Sit in that chair and listen while I sing."
With something simple, like the vanish of a coin, there is a way to tweak it a little to make the whole thing a little more bizarre and intriguing.
Let's assume you have a one coin vanish that ends very clean, with empty hands.
"Can I get your help with something I'm working on?" you ask. "Just hold still, right there for a moment."
Go through the motions of your coin vanish but don't actually do the vanish. Let's say the coin is now sitting in the palm of your hand.
"Can you still see it there?" you ask. They indicate that yes, they can, and you say, "Damn. Uhmmm. Let's try this." Now you rotate your body a small amount to the left or right (whatever direction is more advantageous for your vanish).
Now you do the vanish again, but this time you actually make it disappear. "Can you still see it now?" you ask, as if there is a coin there still to be seen. "No? Awesome. Thanks for your help, What kind of angle are we standing at would you say? 30 degrees?"
Four Ways to Vanish a Coin, Part Two
(Image: Hand On White
, George Hodan, PD)