Strategies to play blackjack online are not different from one developed for the brick and mortar casinos. But, every type of the gaming software has got its rules, and you need to learn what are these rules to apply correct strategy. Major software companies like: Playtech that offers the six deck game and where you are permitted to double the bet after splitting & with any 2 cards; Microgaming that was first software provider to make the fully working casino system online, has the European and the Regular blackjack games; the Boss Media that offers single deck games as well as six deck games; the Realtime Gaming gives games that make use of between 4 - 8 decks; as well as Cryptologic that has eight deck game.

Though casinos online that give single deck blackjack games are now becoming scarcer, you must play at all these casinos in case you may find them, as all these games favor player over dealer. As six deck games appear being the norm online, but, here are a few strategy for this kind of the blackjack games:
In case you have hard 18 or 17, then you must always stand; in case your hand is hard 13 - 16, stand if dealer's face up card is 6 or lower; in case it is higher, you should then hit. Alternatively, in case you have the hard seven, then you must always hit.
In case you have hard 10 or 11, then you must double if rules allow it until dealer's face up card has the value of 10 or higher; and then you must hit.
In case your hand has ace and second card is 6 or below, then stand; if second card is 8 and above, then stand. However, in case you have 2 aces, then split.