Getting Started in Card Counting for Blackjack

Dear Mark, Over the years, I have moved from being a hack blackjack player to one who plays perfect basic strategy. To evolve into an even better player, I am considering counting cards. How important is memory for those of us who have our "senior moments?" Also, where can I find a book on the subject of card counting? Ralph T.
Counting doesn't necessarily take an abundance of gray matter, Ralph. You already know that counting establishes mathematically the degree to which the as-yet-undealt deck favors the dealer or the player. It does this by tracking the changing imbalance of big and little cards in the diminishing deck.
Card counters, theoretically, have an advantage, varying between 0.5% and 1.5%, over the casino. Actual counting is quite simple. A deck that has lost many low cards and is now fat with high cards (10, jack, queen, king, ace) favors the player, while the reverse case, an excess of low cards (2, 3, 4, 5, 6), favors the dealer.
All card-counting systems keep track of the ratio of small cards to big cards remaining in the deck. When that ratio favors the counting player, he/she bets more money; when it favors the dealer, the counter bets less. The simplest count to learn is a one level count, a.k.a. the Hi-Lo counting system. It assigns the following count values to each card.

2, 3, 4, 5, 6 (small cards)....+1
7, 8, 9 (neutral cards).. 0
10, J, Q, K, Ace (big cards)....-1

To use the Hi-Lo method, as the new deck begins, there is as yet no imbalance between the high and low cards except for the possible discard(s), so you visualize a zero as the starting figure. As each card is dealt, you add to or subtract from that imbalance figure the card's value as shown above.
For example, you have played a bit, and now the deck is half gone -- 26 cards remaining. You've been counting, and the current imbalance figure that you have been quietly tracking lies plus-7. Pretty good! If the dealer has to hit his hand, the remaining 26-card deck is short seven of the cards he would like to rely on. But let¹s say he catches his hand with two small cards and the count goes to plus-9 with 24 cards remaining. Many players would bet the farm on the next hand.
You vary your bets, from one hand to the next, guided by the constantly updated imbalance figure, which predicts that the next hand will favor you or favor the dealer.
Final recommendation: Don't quit your day job!