The Suitcase Deadlift puts you in a narrow stance with the bell on the outside of your body. In this position you will really feel the kettlebell trying to pull apart your posture. Try to make it look like you are holding two kettlebells. Keep your shoulders over your hips, over your knees, over your feet. Keep your shoulders down and back. Stay square facing forward. Brace your abs through the movement and squeeze your glutes and quads tight to lockout the top of the lift.
Use this progression for a couple of weeks to gain some ant-rotational strength. Find a weight that you can make 10 reps with and use it for 3-4 sets of 8 reps on each side. Or, choose a heavier weight that you can only do about 6-8 reps with and do 5 sets of 5 reps each side. Avoid fatigue and failure. Make excellent reps.
NOTE: if you can’t get all the way down to the floor without rounding your lower back or compromising your posture in some way; use a block or plyo step to bring the bell closer to you.