As soon as beginning players start to feel comfortable with the game of blackjack, they soon realize that first, they do not know what the reason is for splitting cards and second, they do not know when to do it.
Face Cards. If you split the face cards, you are chancing tossing a 20, which usually wins the hand.
Fours and Fives. If you split fours and fives, you decrease your chances of winning and increase your chances of getting 14s and 15s – not good hands.
What You Should Split
Aces. Split these as two and twelve are of almost no use to the blackjack player; however, if you have two aces, the house rules can be different from casino to casino. Many casinos go by the rule “one draw.” Most of the time casinos do not honor face card/split ace blackjacks.
Eights. The first player who splits eights is more likely to win as opposed to standing on a 16, which is why professionals of blackjack prefer to split only aces and eights. This was discovered when the four horsemen – Herbert Maisel, James McDermott, Wilbert Cantey, Roger Baldwin – decided to run the cards in a mathematical algorithm. These are the men credited with making basic mathematical strategy.