Yes, blackjack has table manners. It is played at a table after all. Actually that is a more relaxed term for blackjack etiquette, and the things that make up blackjack etiquette are kind of like the unwritten rules for blackjack.
Fist off we are going to talk about the cards and touching.
In a face up game the cards are obviously dealt face up on the table by the dealer. He will then quickly calculate the totals. Player then make hand signals to show what play they would like to make: a two finger scratch on the felt for a hit; a palm-down wave over the cards to stand; doubling your amount of chips to signal a double down or a split depending on what cards you have. Hand signals are a part of blackjack etiquette and a tradition of the game. Oh, and they also can back you up if there is some discrepancy on what play you wanted to make since there is a camera above the table.
But above all in a face up blackjack game do NOT touch the cards.
Not touching cards in a face up game prevents players from cheating or marking the cards.
The only type of blackjack game in which you can touch the cards is a face down game. The dealer deals the cards face down and the player picks them up with one hand. Signals in a face down game are a bit different: to hit scrap the cards towards you on the felt to hit; to stand scoot your cards under your wagered chips; to double down or split, turn the cards face up and add the appropriate amount of chips to your wager.
Do NOT use more than one hand to handle your cards.
Handling the cards with one hand helps to cut down on switching or adding cards or marking them for cheating purposes.
You have the etiquette for how to handle your cards down now, and are all set to grab your clip-on tie and head to your favorite casino.