Blackjack basic strategy will optimize your long term returns in blackjack.  In fact, the mathematical house edge in blackjack where the player uses solid basic strategy will be reduced to well below 1%.  Set out below is a basic strategy matrix that shows you the basic strategy move for all deal situations in the most common forms of blackjack.  

The basic strategy play is the move at the intersection of the dealer's card and your hand.

You might want to print this page out for reference during future play.