How to count cards in Blackjack

So how does a card counter keep track of the cards in blackjack? While there are many different systems and variations, counting cards is usually as simple as adding and subtracting the number 1. Subtract one when a high card is dealt and add one when a low card is dealt. The greater the count, the more high cards in the shoe, and the more high cards in the deck, the greater the counting edge for the player.