Squat vs. Deadlift. Image credit: Starting Strength 2nd edition.

The top picture is from the cover of Starting Strength and illustrates 2 technique essentials valid for most weight lifting exercises:

• You must keep the bar above the center of your feet.
• You must move the bar in a straight line.

Keeping the bar above the center of your feet ensures stability. Moving the bar in a straight line is more efficient: the shortest distance between 2 points is a straight line. Here’s how to push/pull the bar in a straight line.

Squat. You’ll always push the bar in a straight line on low bar Squats as long as you keep the bar above the center of your feet.

• Low Bar Position. If you put the bar higher, you’ll lean forward more and risk falling forward. Put the bar on top of your scapular spine.
• Push Your Hips Back. Squatting down kills posterior chain strength and moves the bar away from the center of your feet. Move your hips first.

Overhead Press. Your head is in the way when pressing overhead. Don’t press the bar diagonally. Get your head out of the way so the bar can go up.

• Tilt Head Back. Put the bar close to your clavicles with your elbows up. Look forward while tilting your head back so the bar can go up.
• Shift Torso Forward. Don’t stay behind the bar: get under the bar by shifting your torso forward as soon as the bar reaches forehead level.

Bench Press. Common mistake on the Bench Press is pressing the bar in a diagonal curve: toward your head. Straight line is shorter.

• Tuck Your Elbows. Safer on your shoulders. Tuck your elbows so they end up 45° to your torso rather than perpendicular to your body.
• Touch Your Lower Chest. Lower the bar against your xyphoid process. You can only do this if you keep your elbows tucked.
• Look at The Ceiling. The bar goes where you look. Don’t look at the bar. Fix a point at the ceiling where you want the bar to go.

Deadlift. Starting with the bar away from your shins puts your hips too low, is harder on your lower back, and makes you Deadlift in a \ line.

• Bar Against Shins. Avoid scraped shins by wearing long pants or pulling your socks. Bar against shins in the starting position.
• Keep The Bar Close to You. The closer the bar to your body, the easier the lift. Roll the bar over your thighs on the way up.

Power Clean. Similar error as for Deadlifts: starting the Power Clean with the bar away from your shins because you fear hitting your shins.

• Bar Against Shins. Avoid scraped shins by wearing long pants or pulling your socks. Bar against shins in the starting position.
• Pull from Mid-thigh Level. Don’t pull too soon. Weight until the bar reaches mid-thigh level to start the 2nd pull.
• Touch Your Shirt. The closer the bar, the easier to lift. Touch your shirt at chest level on the way up.

Realize human biomechanics prevent you to push or pull the bar in a perfectly straight line. Strive, however, for a straight bar path. Lower the weight to get used to the new technique if you pushed/pulled differently before.