You and the Dealer: Blackjack
While you don't actually compete against the dealer, or against other players either, in the game of blackjack, the dealer's still the one whose cards you need to beat. Knowing when to hit or when to stop is vital in a game that has almost no margin for error. You certainly can't cheat, but you can use the same thing that poker players use against their opponents - they use tells. A dealer is still a human being, after all.
For the uninitiated, a tell is a reflexive or unintentional transfer of information or communication, which can influence a game against the transmitter. While tells are still present in the game of blackjack, only the dealer's tells matter. Knowing what to look out for can even out the odds. Some people may wonder whether or not they actually are they - simply put, the answer is yes, as the dealer remains a person. They may be professionals, they may technically play more blackjack than you ever will, but they're still people and you can still take advantage of that. While tells may vary from person to person, just like in Texas Hold'em, they're still them. Some tells are notoriously subtle, while others can be seen without effort.
The cards two to six are whether the dealer tells are, as the dealer usually needs to lift the card a little higher for just a little longer just to make sure that he actually doesn't have an ace. The four in particular is notoriously difficult to spot as it looks similar to the top of an ace. No matter how experienced the dealer gets, they still sometimes look twice to make sure that they don't end up playing badly. Face cards are another set of cards that often force a tell. They look very different and can easily be spotted, even with a quick glance, so if the look was faster than usual, then it's probably a face card.
The biggest and most outward dealer tell almost doesn't count as a tell in itself. Sometimes, their hand twitches at an unfortunate moment and they end up revealing their face down card. Normally, this leads to a misdeal, but there are the friendly dealers that simply allow the game to go one.
The tells alone cannot make your game successful. After all, you may end up with a dealer that doesn't have as many tells as you'd like. You need a combination of this along with basic strategies, card counting and betting strategies to consistently make a killing a the casinos. Nevertheless, this is a a viable strategy for any blackjack player worth their salt.