Sorry I took so long to reply, gave a private stage show for college lecturers. (how the educated mind is easier to trick)
I think any tool that a lay person understands is a go for me! If the circumstances are fair enough the performer doesn't look while the subject shuffles, then the subject chooses a card at random and finally it is deduced without holding the packet or having them write it down is ultimately fair.
close up it is always fantastic if you do a mental card force then introduce the deck rather than introduce the deck and get that look people can give
I always borrow a deck (i don't overly use them but just one fast effect) I like to use the 'I don't need to learn lengthy card counting procedures, reading people I found is a lot easier than learning how to remember mass amounts of cards and beside my memory is better used on something I will show you a little later'.
Give them the deck, let them shuffle them while you are facing away they take a card out remember it, put it in anywhere they want and reshuffle. I never touch the cards, look at them tell them to imagine they are playing a game of cards with me and they are holding their card in their hand and then correctly guess the color then suit and finally value.
the kicker for me is teaching someone else the system and getting another subject to guess the card that always works well as they really do use the cues (you will understand if you have purchased the book which i know a few of you have