The aim of Backgammon is to remove all your checkers from the playing board before your opponent. Essentially it is a race, but in this race strategy is very important. Beginners may be tempted to 'hit' opponents but part of the skill of backgammon is implementing strategies to help you win the game with skill.
When playing backgammon distribution of your checkers is worth considering. Having 5 checkers on one point and 1 checker on another is not as strong as having 3 checkers on 2 points. Try and distribute your checkers evenly for protection and so that they can be moved strategically against your opponent.
Don't be tempted to go for the easy shots. You may find hitting your opponent is not as strategic as creating offensive and defensive moves for later in the game.
The best way to improve your strategy is to play other players. By playing online you'll come up against a wide range of players and skill levels. Watch your opponent's moves, how they react in different scenarios and learn from their strategies. There are a number of books that may also help you obtain tips and useful pointers.