Believe it or not, all of us fall into the occasional trap of not paying enough attention to what our opponent is doing and what he or she is trying to accomplish with his or her last move. Many inexperienced chess players get caught up in their own offensive attack and do not keep track of what their opponent is doing in his or her own offensive attack. This is will cause a chess player to lose games unless they break this bad habit.
Every time your opponent makes a move you should stop and think about the following questions. Why was that move chosen? Is one of my pieces in danger? Are there any other threats I should watch out for? What sort of plan does my opponent have in mind? If you can successfully answer these questions before making your next move you will be able to prevent many of your opponent's offensive attacks. Preventing these attacks that your opponent has in the works and then carrying out your own offensive attacks is how you will become dominant in your chess games.
When you learn to envision what your opponent has planned for the next two or three moves you will have a major advantage. Unfortunately, learning the common attacks comes with experience and having played against those attacks. You can speed up your learning though by reviewing games that have been notated. You can review your own past games, or those of grand masters. This will help you to answer the questions that are listed above. These notated games often demonstrate what the different attacks, or intentions of your opponents, might be so that you know what to watch out for.