Develop a Balanced Stance
Practice a balanced three-point stance with your weight evenly distributed. Shifting your weight forward will make it difficult to pass block. Shifting your weight backward will make you slower off the line to run block. If possible, use a left-handed stance to make it easier to block speed rushers on the outside.
Fire Off and Block
Launch into your run block with a good power step at the snap, followed by a quick step. Back into your pass block by pushing off with your inside foot while reaching back with your outside foot. Immediately strike your target in the chest with your free hand. Bend your knees and keep your back straight, creating a strong base with good balance. Keep your shoulder pads low. Use good blocking angles. Learn to sustain blocks for several seconds.
Learn Sound Techniques
Nimble feet are critical for left tackles, who tend to be more athletic than right tackles. Master the kick slide so you can contain outside pass rushers and move inside to thwart stunts and twists. Strike with your hands, recoil and strike again with good "hand punch." Keep defenders at arm's length so they can't get into your body and reduce your leverage. Learn to tie up defenders inside their torso, controlling them without drawing a holding penalty.
Master the Mental Aspects
Learn the playbook thoroughly, study your opponent and learn the tendencies of the player across from you. Know the snap count for each play and listen for adjustments called at the line of scrimmages. Read the defense each time you line up and adjust accordingly. Remain composed, but play with an aggressive edge. Keep battling until the whistle stops play.
Become Bigger, Faster, Stronger
Left tackles must be big, strong and agile. Build total body strength -- legs, core muscles and upper body. Basic lifts like the bench press, front squats and back squats are a good place to start. Pull-ups, medicine ball push-ups and split lifts are also beneficial. Build agility with ladder drills and similar exercises that keep you light on your feet as you get bigger.