A key difference between Blackjack and Spanish 21 is that all 10s are removed from the deck in Spanish 21. A Blackjack occurs when the first two cards that are dealt equal 21 a combination of a face card (Jack, Queen, or King) and an Ace (which can have a value of 1 or 11, depending on your hand).
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.