The defensive line is one of the most essential areas of a football team. If the defensive line performs well, it takes significant pressure off the secondary. You might have average to good cornerbacks on your roster. When asked to cover receivers in one-on-one situations, they struggle after the receiver makes a second move. When the defensive line is playing great football, the cornerbacks don't have to worry about the second move because the quarterback has either had to throw the ball early or he's been sacked.
Get low at the snap of the ball to defeat opposing offensive linemen who are trying to run block. The opposing offense will try to establish the run early in the game. The key to that is winning the battle at the line of scrimmage. The offensive linemen will try to push the defensive line backwards, while the defensive line will try to stop the offensive line in its tracks. By getting underneath their blocks, you will prevent them from run blocking effectively.
Develop an array of moves to rush the passer. Defensive tackles rely on power and one quick move to get up the field, while defensive ends have a little more room to maneuver. Run around the blocker, or use a spin move or your inside shoulder move to get past the offensive tackle.
Keep your hands up once you are on your way to get the quarterback. You may not be able to get to the quarterback, but if you have your hands up you may be able to deflect the pass as the quarterback lets the ball go. A deflected pass will almost fall to the ground, although you may be able to pop it up in the air where one of your defensive teammates can intercept it.
Study your opponent on film so you learn his strengths and weaknesses. It is not just your talent that will help you win the battle. You have to know what your opponent will do when trying to block you. If you can learn his tendencies, you can use countermoves to defeat him. You must have a strategy for each move and employ it quickly, because a pass will leave the quarterback's hand in less than three seconds and you don't have much time.
Work on dropping into coverage. Most of the time, you will be the initial line of defense and you will go straight ahead to try to disrupt a play. However, if the defensive coordinator calls for a zone blitz, the linebackers will go after the quarterback and you will drop back into the passing lanes. You will have to keep your head up to deflect or intercept a pass, or make the tackle after a short pass.