Basic Strategy, which is the absolute mathematically correct way to play every hand, says "Stand on dealer 2 thru 6, otherwise hit".
Why?....
With computer power available, blackjack simulators have been developed, run and analyzed for over 4 billion rounds at all levels of rules, number of decks, etc. The result of that work is Basic Strategy which, while it may look counter to what you want to intuitively believe, is the proven absolute best way to play any given hand.
Here is an example why. Splitting 8,8 when the dealer has a 10 or Ace seems suicidal. You are going to lose in the long run either way, split or not. But you will lose less if you split then if you hit. Losing less on a bad hand is winning!
Learn Basic Strategy is the best advice for all blackjack plays.