Great advice guys.
1. I can't classic palm.. emulation is out.
Then perhaps do a different routine? There's no requirement for a one-coin routine to be part of anyone's act.
IMHO, a one-coin routine is pretty tough to do well - moreso when there's a very useful sleight that's not available (and the ones based on that, like a spider vanish).
If it's any encouragement at all, it took me forever to get a classic palm; I was at the point of giving up before it clicked with me.
To answer your original question more thoroughly, I try to build the routine in such a way as to eliminate any possible method from the minds of the spectator. I start out with a false transfer (left hand to right), then reveal it in the left hand. I do a retention vanish (right hand to left) and reveal it in the right hand. Third time, I do a spider vanish showing both hands 'empty' to derail the though that the coin stays in the other hand. There are a few more phases, one where the vanish happens at eye level (in case they think I'm ditching the coin in the breast pocket), roll up the sleeves in case they think I'm sleeving it, etc.
We give people the experience of the impossible (as opposed to a theatrical depiction of the impossible, like Harry Potter for instance); they should feel that they have seen things happen under test conditions that just aren't possible, and they can only come to that conclusion by ruling out the possible. The routine should have this built into it, that if executed well, there is no explanation within nature for what has just happened. We should give spectators all the answers for when they tell the story about the magician they saw - "it couldn't go up his sleeves, they were rolled up - it didn't go into the pockets, he made it vanish away from them - it was a normal coin, he borrowed it from me - he opened both his hands at once, so it couldn't be in the other hand," and so forth.
On top of that, the presentation has to be engaging, or there's no reason to watch. There's a million ways to present things, so be sure to pick a good one.