Well, I'm not up that heavy yet, but I have hit 405@150 lbs on 3 occasions now.
A tip I got from a friend is to chalk up and get my self psyched up for the lift. I tighten my belt and then walk over to the bar. I first put my right foot in position, then I move my left in. I get both feet nice and wide, toes pointed out and I'm ready to rock. I'm still in a standing position and I take 3 breaths, the last one the biggest and I hold it. Take a quick dip about half way down, then back up quick and then I do my 3 favorite things:
Dip
Grip
Rip
My friend pointed out the fact that he sees many lifters get down and work their grip into the bar and they stay in the bent-over position for too long. He felt this took him out of his zone and took too much out of him. Also, the initial little dip you do before you go down to grab the bar is supposed to somehow do something with kinetic energy that will help your pull off the floor. I don't know if any of this makes sense to you, but since I have made these adjustments my dead has gone up and it just seems easier.