Blackjack rules are generally standardized from casino to casino, but there may be differences in specific rules such as when doubling is allowed and whether the dealer has to hit or stand on a soft 17. If you're not sure what the rules are, find a dealer at an empty or nearly empty table and ask him to explain the rules to you, or watch others play for a while. Most casinos also have brochures or rack cards that spell out the rules for each of their games.

In late 2003, four Las Vegas casinos introduced a variation of blackjack called “royal 20s,” which allows players to make side bets on whether the dealer, the player, or both will be dealt 20. In this variation, suit makes a difference. Two 10-value cards of different suits pays 5:1, but a pair of face cards in the same suit pays 25:1. If this variation on the game takes off, you may see it spring up in casinos around the country.