The fairst of all

You can use any deck for this trick, which the spectator can shuffle. We will use the queen of hearts as the "key" card but you can use another one if you have a special routine.

Start by taking out the queen of hearts from the deck. Show it and say that it's the only card that matches the beauty of the spectator. Put it back on top of the deck.

If you want, you can do an overhand shuffle control or some false cuts to keep it on top.

Next, ask them a number between 1 and 7. Deal that many cards from the deck, grab the one on top of it, and place it on the table. Do the same thing with another number between 8 and 15.

Now say we will use these 2 numbers. Substract these, deal off that many cards and place the card on top of the deck on the table. This card is the queen of hearts. You can do the same thing by adding the 2 numbers, and that will give a totally random card.

Ask the spectator to choose 2 cards between the 2 first and the 2 last. Whatever they say, keep the 2 last cards. Now ask them to put their hands on one of the cards. Again, whatever they do, keep the queen of hearts.

Finally, you can reveal the card that is the queen of hearts.