Being able to defend well in soccer is crucial because about half of the game, your team will not have the ball. Being able to defend as an individual and as a team is essential.
-In nearly all circumstances, when an attacker with the ball is dribbling along the sidelines, push the attacker out of bounds.
-When you are by yourself defending 1-on-1, and the attacker is in the middle of the field, push the attacker to their weak foot. Always assume it is their left foot until they prove you otherwise.
-In game situations where you have an extra defender, and just one person is attacking with the ball, push that player towards the other defender. Four feet attempting to dispossess the attacker is better than two.
-Develop the mindset that defending is just as important as attacking. There is a lot of truth to the saying that "defense wins championships." Even if you are a midfielder or a forward, you still have to improve your ability to defend. For example, a forward that is agile and shifty in their ability to apply pressure in the appropriate game situation will lead to turnovers that will undoubtedly result in goals and assists for the forward that can productively defend.
-Forwards and midfielders shouldn't be too concerned about getting beat by an attacker. Forwards and midfielders should err on the side of having defensive tactics be overly aggressive. Overly aggressive defensive tactics for forwards and midfielders is especially true when the soccer ball is on the other team's half because a penalty on the opposing team's half does not provide a scoring situation or set play for the opposing team. Furthermore, if the forward or defender gets beat, they still have supporting defenders behind them to stop the person that beat them. However, if the midfielder or forward ends up stealing the ball, this can lead to quick counter-attacks that will throw the other team off guard and make it easier to score. Having midfielders and forwards that can defend will result in swift counter-attacks, which is significant because it is a lot easier to dribble or pass the ball by a couple of soccer players rather than an entire team. The quick counter attacks allow for your team to have to beat fewer players to put the ball in the net.
-If your position on the field is indeed a defender, you tend to want to be a tad less aggressive regarding the distance between the person you are marking who has the soccer ball and yourself. Being a tad less aggressive does not mean that you should give less effort or not work intelligently in preventing the opposing team from scoring, it means that you want to give the attacking player in front of you who has the ball a yard or so more of space than a midfielder or forward would provide. Giving a little bit more space as a defender is superior because it is often better to have a player on the opposing team strike a shot from 22 yards away, where the goalkeeper has plenty of time to react and stop the shot than to play too tight the defender. Playing too close to the defender makes it a bit more likely they will dribble past you or take a great first touch past you allowing them to shoot on net 8 yards from the goal instead. If your goalkeeper can't stop a shot from 22+ yards, any goals are primarily on them. However, the best option is to avoid allowing them to dribble around you or take a shot on your net.
-Lastly, great defenders work as a team. It is much harder to dribble and pass around four defenders than it is one defender. Understand that constant talking to let your teammates know about things developing that they can't see and the ability to give constructive feedback on things that did or did not work well for your unit in preventing the other team from scoring is essential in developing the entire defensive squad.
Pick up a copy of the book Soccer Defending: A Step-by-Step Guide on to Stop the Other Team to become a defender that feels good after each game because of how much they stopped the other team.