If you've ever set up for a deadlift, conventional or sumo, you should feel two things.

1. Tension in the hamstrings
2. Tension in the core and lats

What you get results in added stress to the lower back with a suboptimal set up.

First would be to address the initial hinge. Are you feeling it in hamstrings? If not that's the first place you would want to address. A drill I like for that is the butt tap hinge.

From there you continue down, a great cue from Dead Somerset is to squeeze behind your knee continuing to crank up the tension. All before you even grab the barbell or kettlebell. 

At this point you should be over the barbell, from the side view you should have your armpits directly over the barbell once you drop down to the bar.

The goal is always to create tension in the lats without changing the position of your arms. If you retract the shoulder blades aggressively. You want to "squeeze the orange" under your arm pit. 

From there big breath, brace the core, and continue the maintain the tension in the hamstrings and then pull to lockout.