Setup is very important here. I make sure my feet are firmly planted on the ground. I place the bar over my mid foot. Never arch your back during a deadlift. The first thing I do is maintain a neutral spine then flex my core which serves to protect my lower back much like wearing a lifting belt. Never allow tension to leave your core during the lift. Once my entire body including upper back is tight, I begin the deadlift. Hand placement will be slightly wider than shoulder width. Do not jerk the weight off the ground and use momentum to initiate the lift. My legs drive into the ground and begin to raise the weight. As I begin to rise a few inches my upper body begins to rise as well. As I pass the halfway point of the lift my legs and upper body are both extending simultaneously. I squeeze my glutes the entire lift especially as I raise the bar the first few inches. One tip that has greatly helped me is to imagine you are pulling the weight back at an angle instead of just up. This will help you engage the glutes as well.
-Keep knees in a straight path. Do not allow them to buckle in. This is especially important when doing a sumo or wide stance deadlift.
-Always maintain a neutral spine.
-When finishing, do not overly extend backwards. Once upright you have done one rep.
-When using very heavy weight, do not try to lower the weight excessively slow. Although counter intuitive, it is better to use the proper flooring or some rubber plates which allow you to let gravity take back what rightfully belongs to it. This is different than purposefully slamming the weight on the ground. It simply means you do not need to lower the weight at the same speed you raised it.
-When raising the weight you will want the bar to follow the path of your shins. The purpose is to keep the weight close to the center line of your body and protect your lower back. I choose to wear long pants or you can often expect a nice reminder of your dead lift sessions later. When dropping the weight it is difficult to perfectly follow this same path on the way down without smashing your shins. This is why it’s common to slowly lower the bar from the top and then let gravity take over on the second half as you allow it to fall slightly farther forward than the path it took up. If you lowered heavy weight slightly away from your body at a slow speed this creates extra stress on the lower back.