1) It is crucial that you bring your hips up by driving through your heels and engaging your glutes, NOT by arching your low back!!
2) Keep your shins relatively vertical or else your hamstrings will take over.
3) Rest the barbell in your hip crease. I use a foam yoga pad as I've tried most other options and it is the most comfortable by far, especially when you get into the 300's.
4) Before you go, take a deep breath into your belly and surround your spine with air (360 degrees of air) and brace your core. Also, keep your ribs from flaring. This will safeguard your back, and will give you much more ability to generate force.
5) Grip the bar as hard as you can when you are performing this exercise. This will create a ton of tension in your upper body, will safeguard your spine, and will allow you to generate even more force. Very subtle tip and one that I haven't heard before, but I have found that it really works.
6) When you get to the top position, hold for a count or more as this will really utilize the glutes to the max.
7) Choose a weight that allows you to do all of the above.