In general, if you have a hand that totals 17 or higher, you should stand. If your total is between 13 and 16, consider the dealer's up-card before deciding whether to hit or stand. If the dealer's card is 6 or lower, then you should hit; if the dealer has a 7 or higher showing, then you should stand.
Statistician's tips on increasing your odds at blackjack in Las...
Never play 6-5 blackjack. Always insist on the full 3-2 on a winning blackjack. ...
Never take insurance. ...
Surrender 16 against a 10, if allowed. ...
Don't forget the soft doubles. ...
Never make side bets.