Do some pulls standing on about 1-1/2" platform. If your gym has thick 45 lb plates that'll work well to just stand on one of them laying on the floor. Pull like that for a couple of months while wearing shoes then go back to pulling from the floor w/deadlift slippers on and it'll make it feel like a rack pull range of motion, which is freaking sweet.
FWIW I also like pulling against bands, but personally get more out of deficit deads. I get nothing, nada, zilch out of rack pulls.
Additionally, make sure your hips are mobile, especially hip flexors, etc. This can make a huge difference in deadlifts.