The biggest deadlift problem? Not having a proper setup in terms of where the bar path begins and ends.
In short, don't set up where the bar is too far away from your shins. This creates a large lever arm for the lower back and huge sheering forces.
The bar should start right beneath the shoulder blades, close to the shins. This will set you up for a proper pull – the bar will go up and down in a straight line.