Try to use this basic strategy , it might help (it did for me). And if you want more just google it

Blackjack (also known as 21) is one of the most popular casino card games in the world. Much of blackjack's popularity is due to the mix of chance with elements of skill, and the publicity that surrounds card counting (keeping track of which cards have been played since the last shuffle). Blackjack's precursor was vingt-et-un ("twenty-one"), which originated in French casinos around 1700, and did not offer the 3:2 bonus for a two-card 21.
When 21 was first introduced in the United States it was not very popular, so gambling houses tried offering various bonus payouts to get the players to the tables. One such bonus was a 10-to-1 payout if the player's hand consisted of the ace of spades and a black Jack (either the Jack of clubs or the Jack of spades). This hand was called a "blackjack" and the name stuck to the game even though the bonus payout was soon abolished. As the game is currently played, a "blackjack" may not necessarily contain a jack or any black cards at all.
Basic strategy
Because blackjack has an element of player choice, players can reduce casino advantage to less than 1% by playing optimally. The complete set of optimal plays is known as basic strategy. There are slight variations depending on the house rules and number of decks.

The above is a basic strategy table for 3 or more decks, dealer stands on soft 17, double on any 2 cards, double after split allowed, dealer peeks for blackjack, and blackjack pays 3:2. Key:
<!--coloro:#FF0000--><span style="color:#FF0000"><!--/coloro-->S<!--colorc--></span><!--/colorc--> = Stand
<!--coloro:#00FF00--><span style="color:#00FF00"><!--/coloro-->H <!--colorc--></span><!--/colorc-->= Hit
<!--coloro:#48D1CC--><span style="color:#48D1CC"><!--/coloro-->Dh<!--colorc--></span><!--/colorc--> = Double (if not allowed then hit)
<!--coloro:#48D1CC--><span style="color:#48D1CC"><!--/coloro-->Ds<!--colorc--></span><!--/colorc--> = Double (if not allowed then stand)
<!--coloro:#FFFF00--><span style="color:#FFFF00"><!--/coloro-->SP <!--colorc--></span><!--/colorc-->= Split
SU = Surrender (if not allowed, then hit)