The reason that the house always has an edge on us players in blackjack is the simple fact that we have to act first at the table. Every time we hit a card and bust, which happens about 28% of the time, we will lose even though it turns out the dealer busted as well. Basic strategy tells blackjack players when it is the correct time to hit and when they should stand, among other things. The decision is based on the upcard of the dealer and the player’s hand total.
To use the basic strategy, look up your hand along the left vertical edge and the dealer's up card along the top. In both cases an A stands for ace. From top to bottom are the hard totals, soft totals, and splittable hands. There are two charts depending on whether the dealer hits or stands on soft 17.
Other basic strategy rules.
If you play a mixture of six-deck games, some where the dealer hits a soft 17, and some where he stands, and you only wish to memorize one strategy, I would recommend you memorize the one where the dealer stands on soft 17. The cost in errors due to playing the wrong strategy is 2.3 times higher playing a stand on soft 17 game, with the hit on 17 strategy, than vise versa.
For the benefit of my blind readers, here is the above strategy in text form, when the dealer stands on soft 17 and surrender is allowed. To use the strategy, start at the top, and follow the first rule that applies.
As I've said many times, the above strategy will be fine under any set of rules. However, for you perfectionists out there, here are the modifications to make if the dealer hits a soft 17.
My thanks to Kelly for putting together the above text strategy.