False shuffles are very useful when you want to keep a card or possibly a group of cards on the top or the bottom of the pack. They can even be used to transfer a card from the top to bottom or from the bottom to the top of the pack. If this sleight is done well, it looks like you are actually mixing up the cards when in fact you are controlling the deck.
Here are various ways to perform the False Shuffle:
1. One of the easiest false shuffles can be used when you want to keep the bottom card of the pack in position having previously sighted it unbeknown to your spectator. To do this, all you have to do is hold the pack in your left hand in the shuffle position and shuffle the cards in a fairly normal way except that you make sure that the fingers of your left hand keep a grip on the bottom card of the pack. This is further facilitated by dragging off the top card of the pack with the left thumb so that it falls on top of the bottom card and then shuffling the rest of the pack onto the 2 cards.
2. If you want to shuffle this bottom card of the pack to the top than this is also quite easy. All you need to do is perform a normal shuffle then just make sure that the last card pulled by the left thumb to left-hand is a single card. This has to be done very carefully of course because if you pull the last two or three cards over by accident than you will lose control of the position of important card.