The ability to recognize tactics over the board distinguishes a great player from a good player. For this reason, chess players attempt to solve many puzzles when they study the game. Such puzzles can be found in thousands of books and newspapers.
Finding the best move or continuation in these diagrams can dramatically improve your over-the-board play. You will train yourself to recognize certain tactical situations and exploit them when you can.
Another reason why this training is beneficial is because every time you make a move in a chess game, you are solving a different puzzle. While it is important to know strategy and pursue a plan during the course of a game, considering each new position as a puzzle will permit you to consider more plausible plans in the position.
Many beginners find their plan and will play their next dozen moves with that plan in mind giving no consideration to the opponent's plans. A chess game is a constantly changing entity. Every time it is your turn to move, you should attempt to forget the past. Think of yourself as taking over the game for a friend. You must first look deeply into the position in an attempt to understand what is going on.
Once you have a complete understanding of the position, only then can you begin to decide what move to play. Analyze the position; then make your move. You will find that spending a little extra time between moves will be well worth it.