So.....The only real problem I see is your mental approach off of the ground. I know psychologically it is normal to think about "ripping" a weight off the ground, but this is not effective with this and many other lifts. You need to focus on getting set, having your arms fully extended, and lifting from a "locked in" position. What I mean by "locked in" is this: your muscles, all of them, ought to be as engaged as possible prior to the beginning of the lift. This means your posterior chain, your quads, your back, and your arms as much as possible. The deadlift should be a slow controlled motion. This is true for two reasons in my opinion. The first is safety. "Ripping" a maximum effort weight off of the ground while not engaged allows relaxed muscle structure to placed under immense stress trying to get engaged fast. This is where back injuries happen. Second is the concept of rate of force development. If you using a ripping philosophy you will never truly develop maximum force on the lift. With a well controlled motion you will develop peak force around your knees and continue it up throughout the lift, thus vastly increasing your ability to lift heavy. Ripping like this puts your maximum force very close to the ground.
Also, I disagree with practicing more with lower weights. When you get heavy, some form will disappear....especially when heavy is new. Your CNS will take time to adjust to heavy weights and eventually everything will fire appropriately and your form will degrade very little.