In reality, blackjack rules are variated from one casino to another, whether land-based or online, according to a few variables that the house itself will have set. But there are a few too basic constants to get out of the way so you can move on to the meat of the game.
Blackjack uses a standard deck of 52 cards. The suits of the cards are irrelevant, only their numerical values matter. The card values are as follows:
10, J, Q, K = 10
Ace = 1 or 11
Other cards = face value (example: 7 = 7, 8 = 8)
Splitting, doubling down, and getting a natural blackjack are all only possible with a two-card hand. To split, the two-card hand must be a pair.
The common payoff of a natural blackjack is 3:2, or 150% of the original bet. If both the player and the dealer get a blackjack at the same time, it is known as a push. In a push, the player neither wins nor loses, he simply wins back his original bet.
After splitting two Aces, one of the two hands being played may make a blackjack (if a second card just happens to be a 10). Often in these cases, the blackjack resulting from a split is not considered a natural blackjack. Thus, its payoff is 1:1, and not 3:2 as would be for a natural.
As earlier mentioned, the dealer follows his own separate set of blackjack rules. As a standard, if the dealer's hand totals 16 or lower, he must hit; if his hand is 17 or higher, he must stand. These rules are set, which means the dealer does not get to bend the rules in order to gain an advantage over a player.
The initial steps to gaining an edge in a game of blackjack are as much rules as they are strategies. On top of the basic moves of hitting and standing, you also have the choice of splitting and doubling down—and it is with these moves where you start reaping a bigger fortune than what you began with.
Splitting. The favored practice is to always split Aces and 8s, and with good reason. You have a better chance at two new hands with a starting card of Ace or 8 each than with a two-card hand totaling 2 or 16, which is likely to be a low 12 or go over 21 once you are dealt more cards.
Doubling Down. The rule of thumb is to double down when your two-card hand amounts to 9, 10, or 11. It is easy to why: once you are dealt your third card, your hand can come up to 19, 20, 21, which would be hard to beat. Often, it is tempting to not bother doubling down just to be on the safe side. You think you are winning either way, and it does not hurt that you were not able to double those winnings. But realize that every opportunity you let pass by not doubling down and doubling your payoff only increases the house edge to unpleasantly higher levels over your personal advantage. The variable house edge is irrelevant until you turn it to your favor.
Dealer Busting Cards. A dealer up-card with a value of 4, 5, or 6 is known as a "dealer busting card"—that is, a card value that is most likely to cause the dealer's hand to bust. These up-cards, added to a hole card with a highest probable value of 10, make a sum of 14, 15, or 16. Since, as a common rule, the dealer must hit if his hand equals 16 or lower, with a third card added, his hand can get busted. When a dealer is showing busting cards, it is the best time to split or double down.
Only increase your bets when you are winning.
Do not expect to beat the game consistently, even when you are card-counting. A winning streak can not last forever. Instead, set a table limit for yourself, and know when to walk away.
The only time to take insurance is if you have reason to believe that the dealer has a natural blackjack, or if you are card-counting and know that the remaining cards in the deck will not bring you a winning hand.