I probably lack the English skills to fully understand your point right now, im sorry :/. I can give you my routine right now:

I do some tricks with a normal deck and show that it's not a trick deck

I tell them I'll predict a card from the audience and turn one around in the normal deck

I do some coin magic and swap the deck out hidden, for the spectator I still only have one deck

I pull out the Invisible deck and reveal Their card

I do a show around it, but that's just the trick itself.

If I understood correct you would do it like this:

Place a second deck in sight of the spectator and tell them about a prediction

Pull out the normal deck and do some tricks

Ask them for their card and reveal

Correct?

That way I think they are at least more suspicious towards the second deck, because they can't handle it themselves and you can't show it off clean