There are multiple ways of scamming the online blackjack casinos. None of them are illegal, but the Casinos simply don't like that you do it.
By using techniques like card counting and ace locating you can increase your possibilities of winning over the casino dealer. The most basic technique is to count high and low cards. High cards are 10's up to aces and low cards are 2's up to 9's. If you have a deck where you know that most of the cards are High Cards you should bet more because your odds of winning are higher. On the other hand you should not bet to high when the deck is full of low cards.
To understand this, think of the senario that there are a lot of aces and kings in the deck and not so many other cards. The chances of getting something high or even blackjack are very high for you now.
A more advanced trick is to try to follow the hight cards during the game. When the deck is shuffled you try to watch the shuffling and see where your high cards go, and position the splitter so you get lots of hight cards in the beginning. By knowing where the higher cards are located and the lower are, you have some advantage to add to your blackjack gambling. Everything counts, even the cards :)
