In a game that features the 'surrender' option, the player can fold a blackjack hand before drawing new cards. When a player chooses to surrender, half your bet is returned to the stack, and half is forfeited to the dealer.
A basic betting strategy is simply to double the bet after losing a hand, also known as the Martingale system. This can go for multiple hands in a row until you win at blackjack. Then, you reset the bet to the starting value. That one bet will cover your previous losses and even provide a profit.