A basic strategy is to assume the dealer has a 10 face down and hit until you meet or beat their total.

A little more complicated strategy is to always hit on <11 total, always double on a total of 11, hit on 12 to 16 total if the dealer has a 7, 8, 9, 10 otherwise stand, always stand on 17+, and always split Aces, nines, and eights (Never split 10s).

For more specific strategy there are several great online tables that show the best decision for every possible hand are easily googleable.