I believe everybody needs a solid card control. I use a control that I have "created" (similar controls have already been created, but I came up with it on my own) and it can be used to control single or multiple cards to anywhere in the deck-top, bottom, middle between two kings, etc. I feel that this control is the most versatile move I know because you need to control a card in a majority of card tricks, and with just this move and the variations possible there is no need to know another control.